Tools used in this video: R134A Gauge Set with Vacuum Pump: amzn.to/3WRgL4D 1234YF Gauge Set:amzn.to/3WWxd3rMy R134A Gauge Set: amzn.to/3R4IGKz Vacuum Pump: amzn.to/4awnfsF Amazon Store: www.amazon.com/shop/repairgeek Help support the channel, buy using my Amazon links As an Amazon Associate I earn from qualifying purchases and your cost is exactly the same.
Hi Repair Greek! Could you help me repair my car ac system. Have a 2009 mazda 6 the ac was working fine until a few weeks again when it stops and blowing cold air. Checked fuse, relay and compressor clutch all are working OK. Hook up gauge without engine running on a 78 F day Low side was 85 psi, High side 85 psi. With engine running and ac on full blast, no change in readings L 85 psi H 85 psi. If fact after running engine for about 2 minutes high side temp increased to about 90 psi then I shut off engine. Don't know what to do. Please help me as I want to fix it myself. Thanks
You learn something new everyday. I have watched several AC videos recently and yours is the only one that said to evacuate the gauge before connecting it
@@MontyGee-jq6xlbe sure your valves at the service ports are closed when you try pulling the vacuum, or you'll lose all your refrigerant. Close both of the valves at the manifold gauge to isolate the yellow hose before opening the valves at the service ports. I'd have connected the hoses to the service ports with those valves closed while drawing vacuum to check that the gauge set is not leaking while they're connected instead of connecting them after drawing vacuum.
A/C systems are what we call closed loop. In a perfect world, if they don't leak, but in reality as seal age leaks develop. The EASIEST for step for MOST r134 systems is just check your system pressure. No pressure, no run. Pressure switches are installed as safety devices to assure it won't run w/o the lubricant oil you spoke of. After that, if you lost pressure, you have to assume you have a leak. A UV dye is needed to locate the failed seal, then replace and recharge. If you have pressure, then proceed to troubleshoot pressure switches and relays. Always check pressure first. Low side usually needs a minimum of around 30 psi to kick on. If the overall system volume is low, it will run and then stop. This means you still have a leak, but a slow one and might be able to limp through a season with a recharge. Keep in mind, if your system has lost all volume, you'll need a vacuum pump and during recharge you need to add oil. Mech Engineer w/25+ yrs experience. Google what you're not sure of, cause costs can add up fast if you screw it up.
You’ve been responsible for some horrible designs I’d imagine if you have time to type out a comment like this get back to work and ACTUAL MAKE THE WORLD BETTER instead of just spewing basic level knowledge that the content creator is going over anyway.
"Keep in mind, if your system has lost all volume, you'll need a vacuum pump and during recharge you need to add oil." Can you elaborate in regard to the addition of oil in the case of system being completely empty? I am no a/c expert by any means just trying to grasp all concepts and tips before giving this a shot. I am assuming you are referring to the system completely running out of freon when you say lost all volume?
I just bought my manifold qauge set and vacum pump. Getting ready to work on my SUV A/C for the first time in my life !! And I'm 72 years old !! Thanks for the excellent theory class on diagnosing A/C systems !! 😇
@@kylelove927 Not finished yet. I'm going to replace the reciever drier and the expansion valve. But I'm out of money this month. My A/C works fine, just as long as it's below 85 degrees fahrenheit. But here in South Carolina it's going above 90 just about every day, then my A/C produces a 60 degree temp. So I just do all my travel in the morning, and park the SUV in the afternoon. 😭😭😭
The valve stems are the most common leak , right where you hook either gauge , high or low , always check them last , soapy water works for them .@@Crazy-about-cats
THE BEST video I have ever seen describing air conditioning. A refrigeration mechanic told me one time you must understand latent heat evaporation to understand an air conditioning system...then he took about an hour to explain what this guy did in 30 seconds....GREAT VIDEO.
I do refrigeration for a living, and that was an excellent explanation. Well done. Keep up the good work. Thank you for taking the time to film, edit, produce and post this video. You are going to help a lot of DIYers, Mechanics, and Technicians with this video.
0:00 Thanks for a very well explained tutorial, with excellent pointers! Just one thing mentioned by another follower to remember: If you are working on a system that still has refrigerant in it and you do not have a vacuum pump, you still need to purge the blue low pressure line and the red high pressure line besides the obvious yellow hose, before testing the system (for pressures with the gauges). You can do that after hooking up the lines to your car's A/C system per Repair Geek's instructions by very quickly backing off and hand re-tightening the fitting of each hooked up line on the side of the manifold which holds the gauges. You will loose a very small amount of refrigerant from your car's system, but you will ensure the blue and red hoses are free of air and moisture. Otherwise a vacuum pump shoud be used as shown by Repair Geek. Thanks to John!
Worth reiterating on the electrical diagnosis portion: the compressor clutch coil draws a decent bit of current. I once ended up condemning a compressor clutch coil (and the compressor attached to it) because I didn't do a thorough enough diagnosis. Unplugged, a digital voltmeter would show 12V across the pins and I used that as my justification. It turned out that there was another connector upstream in the harness that was loose. It was making a good enough connection to support 12V at the extremely low draw that a digital voltmeter creates. But it would not pass enough current to light a test light. Repairing *that* connector resolved the issue completely.
That's the problem with using a voltmeter for diagnosis, they don't put any real load on the circuit when you check voltage. 95% of all voltage checks can be done with a test light.
I have an '87 Chevy truck that still runs R12. I picked up a half full 30lb tank of R12 from a friend. The label on the tank says to charge with the tank inverted (liquid). I know I would have to do this on the high side. I have a scale and the system takes 3.25 lbs of R12. Is this ok or should I make the switch to R134A? I'm trying to stay original.
I recently changed compressor, condenser, and expansion valve on a 2012 Ford Fusion. It got it working, but, not as cool as I expected. A month later its barely working at all. I have 80 psi on low side and 100 psi on high side, compressor kicking on intermittently. I already figured it was either the compressor or expansion valve which your outstanding video seems to confirm. Now the trick is how to diagnose between those 2 components 🤔
Amazing Video. Been running into a lot of issues lately on my 2015 vehicle. Slowly but surely learning what's going on. But your video is very good. Explaining a lot more in depth than most I've seen. And I've seen a lot. Lol
I’m getting ready to do may ase hvac test. Out of all the video I have watched, this one if by far one of the best. It’s straight forward and gives clear explanations on pressures
The clearest most concise explanation of auto a/c systems and diagnosis I have seen. I would add that not all compressors use a clutch to engage/disengage and appear to be always running. Find out what type you have first before trying to diagnose.
I have say that i appreciate this video as a single mom I really needed someone to explain this to me thank you so mush for the time that your took out of your life to do this need you to know it’s a blessing to bump into these videos with people like you and you make a difference
Happened across this channel to help mw with my AC. First thank you!. All I can say is this the best videos I've watched. He does not use jargon useless to the layman. His approach to instruction is well laid out and easy to understand and follow. Can't wait to view more of his content.
Great job. If you don't have a career in the education system it ll be a waste. I have a college degree and as an inmigrant I can understand you beter that my native language and I bet you can beat any college teacher. Congrats.
I'm just getting into A/C systems... Now auto A/C too. Thank you so much for this easy-to-follow tech A/C training! You take the mystery out of the repair!
Thanks! You helped me more than I can express. This troubleshooting video is the best I have seen on youtube. You are an excellent teacher. Thank you for teaching me. My AC works now after applying your lesson and replacing my expansion valve. I wish I could give you more than $2, but youtube only allow this small amount. Again thank you
I’m a diesel technician and have dealt with AC systems in the dealership that I worked for, but not qualified for it. I recently tried fixing my own field service vehicle’s AC system, but it still doesn’t seem to work 100%. You might be familiar with the Australian and South African Isuzu Dteq and Dmax models with the cracking evaporator issue due to vibration from the engine. I bought it used so I wasn’t sure if mine was part of the problem models. I then bought a new evaporator from our local dealer before stripping the vehicle, after stripping I realised it wasn’t the issue, but fitted the part anyway as it comes with a new expansion valve as part of the unit. Upon fitment and re-gassing the system the AC pump keeps on cycling for like 15mins without switching off and I can smell the AC gas inside the cab. I can’t find any leaks and the system keeps it’s pressure after 3+ days, but I keep on smelling the gas when the AC system operates. Is there a procedure that I can do wrong ? Or is it just me searching for an issue that might not exist ? Or is it possible that there’s a safety valve that dumps the gas ? As I know that AC systems are closed systems and should the gas be low there’s a leak or another underlying issue.
Very well done video. I haven't touched automotive HVAC systems in a long time and your video had me going through a lot of, "Oh! How did I forget about that?" moments throughout watching. Thank you for the time stamps and still putting the fundamental info in this vid together. I'm subscribed.
Great video! I just want to point out one little detail; some systems do utilize both an expansion valve and orifice tube. It's not common, but it does exist. It's found in vehicles that have multiple evaporators, like my Ford Expedition. The front evaporator is metered by an orifice tube, while the rear evaporator is metered by an expansion valve. Just wanted to add that in case somebody has a system like that and wasn't sure why both are available when looking up parts for their vehicle.
EXCELLENT VIDEO. I appreciate especially your comments about the STOP LEAK ( '...best to use it once only ...) ! Great advice, you get right to the point without extra chatter or heavy metal music in the background- no kidding a couple of vids have that !! Looking forward to more. Thank you...
Awesome video; Thank you! 2001 Miata (R-134a) compressor runs fine, warm air out of vent Followed your procedures; low side was low, high side was ok. (10/150 psi) Miata manual says (25/180) Added refrigerant (34/250) air cooler, but still not good… Decided to follow R-134a tem/psi chart - added more refrigerant (55/350) (72° F out of vent / 97° F ambient) actually 102° around engine compartment where I’m measuring. Still not great, but better… car was running for a good 30-45 minutes. Pressures held, compressor didn’t cycle, temp held, etc. Turned engine off and stopped for lunch. Went out to take her out on the road; started up fine, but as soon as engine rpm went up I heard a sound like gas escaping (pressure relief valve?) and air temp from vents immediately got warm. Any help would be greatly appreciated!
Excellent for beginners. Could you do another video that explains these new compressors that have electric control valves that adjust the swage plate. Working on diagnosis of a 2016 BMW 340i, it had a bad clutch. Now it cools for about 15 minutes then disengages the clutch. Not sure how to mechanically check the control valve to see if it's good or bad. Hi and low psi @100. Compressor not engaging, my guess is a stucked closed control valve could keep the pistons at 0% and stop refrigerant flow? Hate these CAN BUS computer controlled systems!
Hi Repair Geek, First of all, Thank you for giving me this opportunity to introduce my self. My name is John and I am DIY Machinic. Now i am 2008 Nissan Rouge. The issue is that the AC System has air and I vacuumed it out and recharge, however whenever i recharge ac can, just went up the Manifold gauge to high and no cold. I checked compressor was also not working i meant the clutch. Do you know what could that be. Any help will be greatly appreciated.. This video was one of the best so far i have watched on RUclips. Thank you again.
I wanted to add that not all compressors have a clutch. There are clutchless variable displacement compressors with a refrigerant control valve. Lots of new cars, especially Euro cars have them and that valve can go bad or not receive the proper pulse width modulated voltage and therefore the compressor will not receive refrigerant.
I have an 87 s-10 that my air conditioning needs to be converted over to the new style. Just trying to throw out a video idea possibly 😅. Good simple straight forward video today 👍
Awesome video! My 99 Silverado AC will work for like 10-15 minutes, and it doesn't blow super cold, but cold enough. But then it starts to blow warm. I shut off the ac switch for a few minutes, turn it back on, and will start to blow cold again. Some mobile mechanic quoted me $1200 to replace compressor, dryer, orifice tube, and condenser. But I want to find out what is causing this, not just change out everything just cuz all the components are over 20 years old. It blows colder at night, and doesn't cut off as much. Once in a while I can hear the AC clutch engaging and disengaging, but it doesn't do that all the time.
Great explanation on how to troubleshoot. Amazing Job!!! I got a question though: I'm getting on my gauge, High pressure on the Low side and Low pressure on the high side. I already replaced compressor (no clutch since is a hybrid) and expansion valve and still having the same issue with very weak AC (meaning not very cold) . There is no leaks in the system. Could this be a clogged evaporator coil? I want to make sure this is the cause before I start the long and tedious work of getting to the evaporator on a Prius. Appreciate if you can point me on the right direction.
Trying to understand the gauges better. The valves closed prevent refrigerant from going "through" to the other side AND escaping via the yellow hose, correct? Similarly, they remain closed so that when you disconnect the yellow from the vacuum you don't then lose your vacuum from the blue-yellow. Where it gets weird for me is that the gauges can register pressures with valves open or closed. I guess if I saw the plumbing I'd understand it better. Great video.
Most yellow hoses have a valve core in them , so it won't back feed as you mentioned , but it will hold a little air in when you first hook it up , so will the blue line , so i try to bleed that air off before i start my charge ..
Thanks Mike. I might locate a more detailed set of instructions for a newbie ... I'm not normally stymied by tools but the Master Cool gauge's paperwork looks oddly cryptic. Had to return it because it arrived from Amazon broken, so now I wait some more.
My wifes car we recovered the freon. Found it to be about a 1.5 lbs low. Weve owned the car for about 8 years and never had it serviced before. Charged the system with a known good charge to specs. Now it cools for about 15 minutes. Gauges will show about 60 on the low and 280 on the high. Ambient temp is 90-95ish. After 20- 25ish minutes the low side will show low at 35 and high side low at 185 and fluctuating as compressor engages and disengages. Thoughts?
I have a 2015 gmc 2500hd. I replaced the condenser and expansion valve, cause the it was only blowing around 65-70* when ambient is above 85*. Vacuumed the system and recharged it with the correct amount. But the low side pressure was close to 5psi low according to the chart. Any insight?
Thanks for the video. This is my scenario, I was adding refrigerant to my ac system, the can was cold as if the refrigerant is coming out feom the system to the can, all of a sudden, the clutch stopped engaging and the gauge goes almost all the way on red. I think about testing it with the vacuum system to see if there's too much refrigerant or not at all in the system Check the AC compressor switch Change the cabine filter And add refrigerant again to see whether it will blow cold air or not. Help me please with more options. Thanks
Amazing video, only question I have and keep forgetting is when you check pressure with manifold gauges you always screw them to open or close?.. this confuses me
Have a 2015 jeep compass. Low side seems normal 35 to 40 on 88° day. High side at 100 psi. It has proper amount of freon and cools good. But high side is off no matter how high rpms are. I've never seen this in a AC. Compressor is new. Note . It cools pretty good.
Great video. But I'm still unsure of my issue. The compressor is taking around 3-4 minutes to kick on which I know is not right. Ambient temp is 92. Pressures are 150H 90L @1500 RPM until the compressor finally kicks on. When the compressor is running the pressures are 200H 60L @1500 RPM and starts blowing fairly cold. I appreciate any advice!
Vac pump not needed before connecting hoses, leave fittings a little loose on gage set, connect to car, let system pressure purge out air, just a little, doesn’t take much. Otherwise excellent.
Thanks for confirming. For two days now, doing homework on RUclips on how to properly purge the air out of the low and high pressure hose on a a/c system that still has some 134a in it, I only found one besides your note explaining how to simply purge air out of the Blue and Red hose. Everybody talks about clearing the yellow hose with a squirt from the can, but no one seems to mention the other important hoses. Thank you for confirming. Of all the videos out there, Repair Geek is doing a fine job explaining otherwise. I'm glad I watched it.
Thank you for your most informative videos. If any cold air is coming out of the vents in the car, is it fair to say that the compressor is engaging and one can eschew testing the compressor for power and ground, testing AC clutch relay, and checking the clutch itself? Is there a visual/audible test to know if the compressor is turning on and the clutch is engaging? Is there a way to remove the AC clutch relay and check it somehow with a multi-meter or that? I have a 2015 Ford Police Interceptor Utility (Police Ford Explorer) and as far as I know the drier has never been replaced. Even though some cold air is coming out of the system, do you recommend replacing the drier because it likely has expended all its desiccant since 2015? I have owned the car since 2017 and live in Nevada (desert climate) and the drier has never been replaced since I owned the vehicle. I was told that at some point (not knowing the full history of the vehicle) it is good to evacuate all the refrigerant from the AC system, use a pump to remove any air or moisture as well, and then refill the system with refrigerant. I would imagine if I am going to replace the drier, then I'd need to do all this anyway in precedence to replacing the drier?
Thanks for this video, very helpful although I do have a question... I have a 2017 KIA sportage (1234yf), I checked the pressures at 65 deg and get the following compressor off: Lside 62, Hside 98 compresson on: Lside drops to 40 (normal is 28-38), Hside climbs to 128 and holds for a sec before the compressor kicks off (normal ranges 135-154) . The compressor stays off for about 35 sec before the cycle repeats at idle. When the compressor kicks off, the cooling fan comes on for about 15 sec. Any thoughts?
Great vid, thank you! Im trying to diagnose 75° air coming through my vents. I've read small clips that getting moisture/air in the lines cam also result in normal high & low side pressures with reduced efficiency. I am one of those people who top off on an annual basis (without vacuum bleeding lines first), and have been known to use a can wuth stop leak. What do you think? Condenser looks pretty clean, but to even inspect the evap core requires removal of the entire dash, disconnecting evap and heater core, and removing the entire hvac box in my 2005 Ram truck.
Great info and video - Thanks. Question; assuming charge is low, should I use the gauges to add refrigerant (and if so, how?) or just use the little 12” hose you can get at the parts stores. I feel like those let air into the system and don’t evacuate all of the can. Also, if low side pressure is 30psi, then the refrigerant can will never empty to a pressure less than 30psi. Or, am I missing something?? Thanks!
Curious question on pulling a vacuum on the a/c system. If I already have refrigerant in the system, does pulling a vacuum remove the refrigerant from the system or does it remain?
Great information. I was looking at vaccum pumps on amazon and they range from 3 to 7.2 cfm. Is there any benefits to higher cfm orher than speed? Some are single stage and some are 2 stage? Any benefit to eirher one? Thanks
Im having a high psi on low side and low psi on high side. My compressor is engaged and the psi is still high on low side and low on high side. So im thinking maybe expansion valve stuck open or compressor work out
Question, I have a 2001 Dodge ram 1500, with the 5.9L 4x4. I have an orifice tube, not an expansion valve. That line from the condenser runs to the orifice tube, then runs to the evaporator core and then from there to the accumulator and then from there, it goes to the compressor. So my problem is the AC line coming from the orifice tube to the evaporator when the AC is on full blast there is a lot of condensation on it. Eventually it turns to ice. So any advice is appreciated.
Hello my friend, thanks for this beautiful video, specially create for you to people like us. I did it, my Toyota Rav4 2011 after connecting the gauges was marking 20 in low and 130 in high, after applied r134a (1 can 12 ounces) it reached 30 in low and 180 in high, i am living in Palm Springs, the ambient temperature was 100 F. Do you think that i must add another Can? the inside temperature if my car, measuring straight in the AC vent is 41 F. i measured the temperature also in the rear seat reaching 60 F. waiting for your best advice. Thanks again.
hello!! excellent video. My brother had a hose replaced and it was not getting cold enough in the cabin, but I also noticed that not enough air was coming out of the 2 ducts on the pilot's side. Could that be the problem, the pressures at the Gates were in the correct range!!
I see you didn't mention measuring the freon to put it in What scale would you recommend for measuring the freon weight Thank you beforehand absolutely excellent video
I have 11yo Honda Civic. The AC gradually started to cool not as good - I never serviced it yet during these 11years. I will check the high/low pressures. I guess it will need some charge. Do you have a video or good reference how to add charge to the car AC correctly? I have a digital manifold, hoses, vacuum pump, vacuum gauge and the scale.
I have the same exact car 08 Honda.. had the compressor replaced a few years ago .. but this summer I noticed my ac only cools when I’m driving,and not well ,, it stops cooling when I’m at a stop or at idol…
Would like to know I go to charge up system freon goes in gauges reads right but once the can is empty gauges go to both sides go back to 0 was wondering is that the evaporator?
great explanation. how would you know if you need to add oil or the system needs oil? how much would you use? can a scan tool tell you if the compressor is working in the special function?
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What about a low side normal but a high side that keeps climbing? Low line is only cold where it’s leaving condenser.
Hi Repair Greek! Could you help me repair my car ac system. Have a 2009 mazda 6 the ac was working fine until a few weeks again when it stops and blowing cold air. Checked fuse, relay and compressor clutch all are working OK. Hook up gauge without engine running on a 78 F day Low side was 85 psi, High side 85 psi. With engine running and ac on full blast, no change in readings L 85 psi H 85 psi. If fact after running engine for about 2 minutes high side temp increased to about 90 psi then I shut off engine. Don't know what to do. Please help me as I want to fix it myself. Thanks
@@williamp6595z😅😅😅😅u😅😅u😅u😅uy😅😅u😅d😅u😅d😅😅😅😅😅😅😅😅😅😅😅😅😅😅😅😅do 😅😅not 😅😅
@@cardonn364this guy a beta male
You learn something new everyday. I have watched several AC videos recently and yours is the only one that said to evacuate the gauge before connecting it
Do you keep the vacuum hooked up and just close the valves before connecting hs/ls hoses?
@@MontyGee-jq6xl I did (not running) but I don't know if it is necessary
@@MontyGee-jq6xlbe sure your valves at the service ports are closed when you try pulling the vacuum, or you'll lose all your refrigerant.
Close both of the valves at the manifold gauge to isolate the yellow hose before opening the valves at the service ports.
I'd have connected the hoses to the service ports with those valves closed while drawing vacuum to check that the gauge set is not leaking while they're connected instead of connecting them after drawing vacuum.
A/C systems are what we call closed loop. In a perfect world, if they don't leak, but in reality as seal age leaks develop. The EASIEST for step for MOST r134 systems is just check your system pressure. No pressure, no run. Pressure switches are installed as safety devices to assure it won't run w/o the lubricant oil you spoke of. After that, if you lost pressure, you have to assume you have a leak. A UV dye is needed to locate the failed seal, then replace and recharge. If you have pressure, then proceed to troubleshoot pressure switches and relays. Always check pressure first. Low side usually needs a minimum of around 30 psi to kick on. If the overall system volume is low, it will run and then stop. This means you still have a leak, but a slow one and might be able to limp through a season with a recharge. Keep in mind, if your system has lost all volume, you'll need a vacuum pump and during recharge you need to add oil. Mech Engineer w/25+ yrs experience. Google what you're not sure of, cause costs can add up fast if you screw it up.
Excellent post
Thank you
You’ve been responsible for some horrible designs I’d imagine if you have time to type out a comment like this get back to work and ACTUAL MAKE THE WORLD BETTER instead of just spewing basic level knowledge that the content creator is going over anyway.
"Keep in mind, if your system has lost all volume, you'll need a vacuum pump and during recharge you need to add oil."
Can you elaborate in regard to the addition of oil in the case of system being completely empty? I am no a/c expert by any means just trying to grasp all concepts and tips before giving this a shot. I am assuming you are referring to the system completely running out of freon when you say lost all volume?
Thank you for taking the time to explain so well, very helpful video!🤗🇵🇷
I just bought my manifold qauge set and vacum pump. Getting ready to work on my SUV A/C for the first time in my life !! And I'm 72 years old !! Thanks for the excellent theory class on diagnosing A/C systems !! 😇
Hey old man. How'd your AC job turn out? Got that thing nice and cold I hope.
@@kylelove927 Not finished yet. I'm going to replace the reciever drier and the expansion valve. But I'm out of money this month. My A/C works fine, just as long as it's below 85 degrees fahrenheit. But here in South Carolina it's going above 90 just about every day, then my A/C produces a 60 degree temp. So I just do all my travel in the morning, and park the SUV in the afternoon. 😭😭😭
@@Crazy-about-cats 1 step at a time. Keep your head up.
The valve stems are the most common leak , right where you hook either gauge , high or low , always check them last , soapy water works for them .@@Crazy-about-cats
@@MikeSmith-nu9wt Yes I know, After I discharged the Freon into the atmosphere 😱 I put two new A/C valve cores in. 😇
I'm no A/C tech, but I have installed Auto A/C systems, evacuated them, charged them, etc. This video seems really thorough and well explained.
THE BEST video I have ever seen describing air conditioning. A refrigeration mechanic told me one time you must understand latent heat evaporation to understand an air conditioning system...then he took about an hour to explain what this guy did in 30 seconds....GREAT VIDEO.
I do refrigeration for a living, and that was an excellent explanation. Well done. Keep up the good work. Thank you for taking the time to film, edit, produce and post this video. You are going to help a lot of DIYers, Mechanics, and Technicians with this video.
0:00 Thanks for a very well explained tutorial, with excellent pointers! Just one thing mentioned by another follower to remember: If you are working on a system that still has refrigerant in it and you do not have a vacuum pump, you still need to purge the blue low pressure line and the red high pressure line besides the obvious yellow hose, before testing the system (for pressures with the gauges). You can do that after hooking up the lines to your car's A/C system per Repair Geek's instructions by very quickly backing off and hand re-tightening the fitting of each hooked up line on the side of the manifold which holds the gauges. You will loose a very small amount of refrigerant from your car's system, but you will ensure the blue and red hoses are free of air and moisture. Otherwise a vacuum pump shoud be used as shown by Repair Geek.
Thanks to John!
Worth reiterating on the electrical diagnosis portion: the compressor clutch coil draws a decent bit of current. I once ended up condemning a compressor clutch coil (and the compressor attached to it) because I didn't do a thorough enough diagnosis. Unplugged, a digital voltmeter would show 12V across the pins and I used that as my justification.
It turned out that there was another connector upstream in the harness that was loose. It was making a good enough connection to support 12V at the extremely low draw that a digital voltmeter creates. But it would not pass enough current to light a test light. Repairing *that* connector resolved the issue completely.
That's the problem with using a voltmeter for diagnosis, they don't put any real load on the circuit when you check voltage. 95% of all voltage checks can be done with a test light.
I have an '87 Chevy truck that still runs R12. I picked up a half full 30lb tank of R12 from a friend. The label on the tank says to charge with the tank inverted (liquid). I know I would have to do this on the high side. I have a scale and the system takes 3.25 lbs of R12.
Is this ok or should I make the switch to R134A? I'm trying to stay original.
I recently changed compressor, condenser, and expansion valve on a 2012 Ford Fusion. It got it working, but, not as cool as I expected. A month later its barely working at all. I have 80 psi on low side and 100 psi on high side, compressor kicking on intermittently. I already figured it was either the compressor or expansion valve which your outstanding video seems to confirm. Now the trick is how to diagnose between those 2 components 🤔
@@ericponta9771 80 ? No wonder mfker don't work!!
Amazing Video. Been running into a lot of issues lately on my 2015 vehicle. Slowly but surely learning what's going on. But your video is very good. Explaining a lot more in depth than most I've seen. And I've seen a lot. Lol
I’m getting ready to do may ase hvac test. Out of all the video I have watched, this one if by far one of the best. It’s straight forward and gives clear explanations on pressures
The clearest most concise explanation of auto a/c systems and diagnosis I have seen. I would add that not all compressors use a clutch to engage/disengage and appear to be always running. Find out what type you have first before trying to diagnose.
Like Toyota rav4 2014 le
Excellent tutorial video, greatly appreciated. Thankyou, hi from down under. 👍
I have say that i appreciate this video as a single mom I really needed someone to explain this to me thank you so mush for the time that your took out of your life to do this need you to know it’s a blessing to bump into these videos with people like you and you make a difference
Happened across this channel to help mw with my AC. First thank you!. All I can say is this the best videos I've watched. He does not use jargon useless to the layman. His approach to instruction is well laid out and easy to understand and follow. Can't wait to view more of his content.
From now on i am a Car A/C specialist, Top Teacher
Great job. If you don't have a career in the education system it ll be a waste. I have a college degree and as an inmigrant I can understand you beter that my native language and I bet you can beat any college teacher. Congrats.
This is the best explanation of this system i've heard so far. Congrats, man! Wish your channel lots of success.
I'm just getting into A/C systems... Now auto A/C too. Thank you so much for this easy-to-follow tech A/C training! You take the mystery out of the repair!
Thanks! You helped me more than I can express. This troubleshooting video is the best I have seen on youtube. You are an excellent teacher. Thank you for teaching me. My AC works now after applying your lesson and replacing my expansion valve. I wish I could give you more than $2, but youtube only allow this small amount. Again thank you
Greatly appreciated!
I like your approach..simple, clear and easy to understand..thanks for sharing.
Excellent video, as a life long motorcycle tech I never did much with AC, but now I am retired and want to fix my own. Thanks
AWESOME video, exactly what I needed for my car, and it’s getting hot out! Thanks
Excellent work helping me read the gauges and explaining possible causes for each scenario
I’m a diesel technician and have dealt with AC systems in the dealership that I worked for, but not qualified for it. I recently tried fixing my own field service vehicle’s AC system, but it still doesn’t seem to work 100%. You might be familiar with the Australian and South African Isuzu Dteq and Dmax models with the cracking evaporator issue due to vibration from the engine. I bought it used so I wasn’t sure if mine was part of the problem models.
I then bought a new evaporator from our local dealer before stripping the vehicle, after stripping I realised it wasn’t the issue, but fitted the part anyway as it comes with a new expansion valve as part of the unit. Upon fitment and re-gassing the system the AC pump keeps on cycling for like 15mins without switching off and I can smell the AC gas inside the cab. I can’t find any leaks and the system keeps it’s pressure after 3+ days, but I keep on smelling the gas when the AC system operates. Is there a procedure that I can do wrong ? Or is it just me searching for an issue that might not exist ? Or is it possible that there’s a safety valve that dumps the gas ? As I know that AC systems are closed systems and should the gas be low there’s a leak or another underlying issue.
Very well done video. I haven't touched automotive HVAC systems in a long time and your video had me going through a lot of, "Oh! How did I forget about that?" moments throughout watching. Thank you for the time stamps and still putting the fundamental info in this vid together. I'm subscribed.
Excellent Video/Tutorial on air conditioning systems and troubleshooting them. Thank you.
Great video! I just want to point out one little detail; some systems do utilize both an expansion valve and orifice tube. It's not common, but it does exist. It's found in vehicles that have multiple evaporators, like my Ford Expedition. The front evaporator is metered by an orifice tube, while the rear evaporator is metered by an expansion valve. Just wanted to add that in case somebody has a system like that and wasn't sure why both are available when looking up parts for their vehicle.
Best video on this I've seen! Great job!!
I replayed your video and made an ambient temperature table as well as a Low side / High side lo-hi diagnostic chart
Any way to share?
@@MichaelPSmith-mp1fk Just pause the video and take a picture or write down the info.
Excellent tutorial. Thanks for sharing.
EXCELLENT VIDEO. I appreciate especially your comments about the STOP LEAK ( '...best to use it once only ...) !
Great advice, you get right to the point without extra chatter or heavy metal music in the background- no kidding a couple of vids have that !! Looking forward to more. Thank you...
DONTever use stop leak .it dosent worl and clogs up internal scilcar gell
Thank your for sharing your knowledge your an awesome teacher as well
My friend, this video is amazing! Thank you so much.
Awesome video; Thank you!
2001 Miata (R-134a) compressor runs fine, warm air out of vent
Followed your procedures; low side was low, high side was ok. (10/150 psi) Miata manual says (25/180)
Added refrigerant (34/250) air cooler, but still not good…
Decided to follow R-134a tem/psi chart - added more refrigerant (55/350)
(72° F out of vent / 97° F ambient) actually 102° around engine compartment where I’m measuring.
Still not great, but better… car was running for a good 30-45 minutes.
Pressures held, compressor didn’t cycle, temp held, etc.
Turned engine off and stopped for lunch.
Went out to take her out on the road; started up fine, but as soon as engine rpm went up I heard a sound like gas escaping (pressure relief valve?) and air temp from vents immediately got warm.
Any help would be greatly appreciated!
Outstanding video brother. My 2002 Camry problem was a bad AC relay as well. And it has a sight glass which I love.
I have watched a lot of videos and got to say yours is the best. Keep up the great work my friend
Bro this guy is smart
Thanks and keep up the great charity!
Absolutely brilliant video
Learned so much from this video. Great video, great bullet points.
And you covered the major symptoms for the most common issues.
Thanks!
This guy is really good at explaining,keep doing it cause you are really good!my respect!
Thank you, this video helps me get fully understand of the AC system work in car..
Thanks for sharing your know-how. I really appreciated it.
How to use a allway caulk tool
Good easy to understand info said very well. Thanks for sharing
Great video boss.i am a ac technician
Excellent for beginners. Could you do another video that explains these new compressors that have electric control valves that adjust the swage plate. Working on diagnosis of a 2016 BMW 340i, it had a bad clutch. Now it cools for about 15 minutes then disengages the clutch. Not sure how to mechanically check the control valve to see if it's good or bad. Hi and low psi @100. Compressor not engaging, my guess is a stucked closed control valve could keep the pistons at 0% and stop refrigerant flow? Hate these CAN BUS computer controlled systems!
Hi Repair Geek, First of all, Thank you for giving me this opportunity to introduce my self. My name is John and I am DIY Machinic. Now i am 2008 Nissan Rouge. The issue is that the AC System has air and I vacuumed it out and recharge, however whenever i recharge ac can, just went up the Manifold gauge to high and no cold. I checked compressor was also not working i meant the clutch. Do you know what could that be. Any help will be greatly appreciated.. This video was one of the best so far i have watched on RUclips. Thank you again.
I wanted to add that not all compressors have a clutch. There are clutchless variable displacement compressors with a refrigerant control valve. Lots of new cars, especially Euro cars have them and that valve can go bad or not receive the proper pulse width modulated voltage and therefore the compressor will not receive refrigerant.
Yeah a mechanic tried replacing my rcv but still no Dice, so either compressor or expansion valve like explained in this video
he has did a better job than most.
I have an 87 s-10 that my air conditioning needs to be converted over to the new style. Just trying to throw out a video idea possibly 😅. Good simple straight forward video today 👍
I would do one but I don't have anything that needs to be converted 😅
great job explaining the system i will share this with some most likely
Awesome video! My 99 Silverado AC will work for like 10-15 minutes, and it doesn't blow super cold, but cold enough. But then it starts to blow warm. I shut off the ac switch for a few minutes, turn it back on, and will start to blow cold again. Some mobile mechanic quoted me $1200 to replace compressor, dryer, orifice tube, and condenser. But I want to find out what is causing this, not just change out everything just cuz all the components are over 20 years old. It blows colder at night, and doesn't cut off as much. Once in a while I can hear the AC clutch engaging and disengaging, but it doesn't do that all the time.
Excellent video. Thanks for sharing.
Very good, on target. Thanks
Great video! This really was informative!
Great video. Thank you.
Great ac troubleshooting tips thank u
Thank you! Very good information
Great explanation on how to troubleshoot. Amazing Job!!! I got a question though: I'm getting on my gauge, High pressure on the Low side and Low pressure on the high side. I already replaced compressor (no clutch since is a hybrid) and expansion valve and still having the same issue with very weak AC (meaning not very cold) . There is no leaks in the system. Could this be a clogged evaporator coil? I want to make sure this is the cause before I start the long and tedious work of getting to the evaporator on a Prius. Appreciate if you can point me on the right direction.
Very well explained 👍
Trying to understand the gauges better. The valves closed prevent refrigerant from going "through" to the other side AND escaping via the yellow hose, correct? Similarly, they remain closed so that when you disconnect the yellow from the vacuum you don't then lose your vacuum from the blue-yellow.
Where it gets weird for me is that the gauges can register pressures with valves open or closed. I guess if I saw the plumbing I'd understand it better. Great video.
You're correct on how the valves work. The gauges just read the pressure in the red and blue hoses.
Most yellow hoses have a valve core in them , so it won't back feed as you mentioned , but it will hold a little air in when you first hook it up , so will the blue line , so i try to bleed that air off before i start my charge ..
Thanks Mike. I might locate a more detailed set of instructions for a newbie ... I'm not normally stymied by tools but the Master Cool gauge's paperwork looks oddly cryptic. Had to return it because it arrived from Amazon broken, so now I wait some more.
This is a proper video. Good explanation of how things work, with diagnostic tips. Not a parts changer. Thanks.
Informative!! How about pressure should be when running front and and rear ac separately or both at same time?
If u recharge ac unit do u have to add oil again?
great teaching bra! good stuff
My wifes car we recovered the freon. Found it to be about a 1.5 lbs low. Weve owned the car for about 8 years and never had it serviced before. Charged the system with a known good charge to specs. Now it cools for about 15 minutes. Gauges will show about 60 on the low and 280 on the high. Ambient temp is 90-95ish. After 20- 25ish minutes the low side will show low at 35 and high side low at 185 and fluctuating as compressor engages and disengages. Thoughts?
Thank you for an excellent presentation!
Great video…really well done man! 👍
wow! for me yes, it's clear and helpful for a beginer!
I have a 2015 gmc 2500hd. I replaced the condenser and expansion valve, cause the it was only blowing around 65-70* when ambient is above 85*. Vacuumed the system and recharged it with the correct amount. But the low side pressure was close to 5psi low according to the chart. Any insight?
Thanks for the video. This is my scenario, I was adding refrigerant to my ac system, the can was cold as if the refrigerant is coming out feom the system to the can, all of a sudden, the clutch stopped engaging and the gauge goes almost all the way on red.
I think about testing it with the vacuum system to see if there's too much refrigerant or not at all in the system
Check the AC compressor switch
Change the cabine filter
And add refrigerant again to see whether it will blow cold air or not.
Help me please with more options.
Thanks
Amazing video, only question I have and keep forgetting is when you check pressure with manifold gauges you always screw them to open or close?.. this confuses me
Close
🤔..... Hmmmm
Have a 2015 jeep compass. Low side seems normal 35 to 40 on 88° day. High side at 100 psi. It has proper amount of freon and cools good. But high side is off no matter how high rpms are. I've never seen this in a AC. Compressor is new. Note . It cools pretty good.
Great video. But I'm still unsure of my issue. The compressor is taking around 3-4 minutes to kick on which I know is not right. Ambient temp is 92. Pressures are 150H 90L @1500 RPM until the compressor finally kicks on. When the compressor is running the pressures are 200H 60L @1500 RPM and starts blowing fairly cold. I appreciate any advice!
Vac pump not needed before connecting hoses, leave fittings a little loose on gage set, connect to car, let system pressure purge out air, just a little, doesn’t take much. Otherwise excellent.
Thanks for confirming. For two days now, doing homework on RUclips on how to properly purge the air out of the low and high pressure hose on a a/c system that still has some 134a in it, I only found one besides your note explaining how to simply purge air out of the Blue and Red hose. Everybody talks about clearing the yellow hose with a squirt from the can, but no one seems to mention the other important hoses. Thank you for confirming.
Of all the videos out there, Repair Geek is doing a fine job explaining otherwise.
I'm glad I watched it.
What about an issue where the system blows cold when the ambient temp is low, but only cold when "highway traveling" in higher ambient temps?
Thank you for your most informative videos.
If any cold air is coming out of the vents in the car, is it fair to say that the compressor is engaging and one can eschew testing the compressor for power and ground, testing AC clutch relay, and checking the clutch itself?
Is there a visual/audible test to know if the compressor is turning on and the clutch is engaging?
Is there a way to remove the AC clutch relay and check it somehow with a multi-meter or that?
I have a 2015 Ford Police Interceptor Utility (Police Ford Explorer) and as far as I know the drier has never been replaced. Even though some cold air is coming out of the system, do you recommend replacing the drier because it likely has expended all its desiccant since 2015? I have owned the car since 2017 and live in Nevada (desert climate) and the drier has never been replaced since I owned the vehicle.
I was told that at some point (not knowing the full history of the vehicle) it is good to evacuate all the refrigerant from the AC system, use a pump to remove any air or moisture as well, and then refill the system with refrigerant. I would imagine if I am going to replace the drier, then I'd need to do all this anyway in precedence to replacing the drier?
I have a question. If my pressure readings are normal but still not cooling can it be my expansion valve stuck open? 😇😇😇
Thanks for this video, very helpful although I do have a question... I have a 2017 KIA sportage (1234yf), I checked the pressures at 65 deg and get the following
compressor off: Lside 62, Hside 98
compresson on: Lside drops to 40 (normal is 28-38), Hside climbs to 128 and holds for a sec before the compressor kicks off (normal ranges 135-154) . The compressor stays off for about 35 sec before the cycle repeats at idle. When the compressor kicks off, the cooling fan comes on for about 15 sec.
Any thoughts?
Great vid, thank you! Im trying to diagnose 75° air coming through my vents. I've read small clips that getting moisture/air in the lines cam also result in normal high & low side pressures with reduced efficiency. I am one of those people who top off on an annual basis (without vacuum bleeding lines first), and have been known to use a can wuth stop leak. What do you think? Condenser looks pretty clean, but to even inspect the evap core requires removal of the entire dash, disconnecting evap and heater core, and removing the entire hvac box in my 2005 Ram truck.
Great info and video - Thanks.
Question; assuming charge is low, should I use the gauges to add refrigerant (and if so, how?) or just use the little 12” hose you can get at the parts stores. I feel like those let air into the system and don’t evacuate all of the can. Also, if low side pressure is 30psi, then the refrigerant can will never empty to a pressure less than 30psi. Or, am I missing something??
Thanks!
Awesome job, thanks.
Curious question on pulling a vacuum on the a/c system. If I already have refrigerant in the system, does pulling a vacuum remove the refrigerant from the system or does it remain?
Excellent job...but a basic test is feel..feel the lines for temp..where hot where cold..why ?
Great information. I was looking at vaccum pumps on amazon and they range from 3 to 7.2 cfm. Is there any benefits to higher cfm orher than speed? Some are single stage and some are 2 stage? Any benefit to eirher one? Thanks
Excellent tutorial.
Im having a high psi on low side and low psi on high side. My compressor is engaged and the psi is still high on low side and low on high side. So im thinking maybe expansion valve stuck open or compressor work out
Question, I have a 2001 Dodge ram 1500, with the 5.9L 4x4. I have an orifice tube, not an expansion valve. That line from the condenser runs to the orifice tube, then runs to the evaporator core and then from there to the accumulator and then from there, it goes to the compressor. So my problem is the AC line coming from the orifice tube to the evaporator when the AC is on full blast there is a lot of condensation on it. Eventually it turns to ice. So any advice is appreciated.
Hello my friend, thanks for this beautiful video, specially create for you to people like us. I did it, my Toyota Rav4 2011 after connecting the gauges was marking 20 in low and 130 in high, after applied r134a (1 can 12 ounces) it reached 30 in low and 180 in high, i am living in Palm Springs, the ambient temperature was 100 F. Do you think that i must add another Can? the inside temperature if my car, measuring straight in the AC vent is 41 F. i measured the temperature also in the rear seat reaching 60 F. waiting for your best advice. Thanks again.
So we leave the yellow line connected to the vacuum pump the entire time we are checking the gauge readings?
Very good video.
Great video.. thanks!!
Excellent!
hello!! excellent video. My brother had a hose replaced and it was not getting cold enough in the cabin, but I also noticed that not enough air was coming out of the 2 ducts on the pilot's side. Could that be the problem, the pressures at the Gates were in the correct range!!
You have an issue with the dual zone climate control not the AC. If one side is hot and the other is cold the AC isn't the problem.
@@RepairGeek thanks for your time 🙏
Great Video
Thank you!
I see you didn't mention measuring the freon to put it in
What scale would you recommend for measuring the freon weight
Thank you beforehand absolutely excellent video
Diagnosis is the word that is covered .... 😂 ... might be the reason why you didn't get told how much refrigerate/ oil goes in.
I have 11yo Honda Civic. The AC gradually started to cool not as good - I never serviced it yet during these 11years. I will check the high/low pressures. I guess it will need some charge. Do you have a video or good reference how to add charge to the car AC correctly? I have a digital manifold, hoses, vacuum pump, vacuum gauge and the scale.
I have the same exact car 08 Honda.. had the compressor replaced a few years ago .. but this summer I noticed my ac only cools when I’m driving,and not well ,, it stops cooling when I’m at a stop or at idol…
Would like to know I go to charge up system freon goes in gauges reads right but once the can is empty gauges go to both sides go back to 0 was wondering is that the evaporator?
If I did not vacuum gauge set before charging is this a huge problem?
And great video!
great explanation. how would you know if you need to add oil or the system needs oil? how much would you use? can a scan tool tell you if the compressor is working in the special function?
you cannot mesure the oil leval .put right amount in when you regas