Troubleshooting Indicators for a Liquid Line Restriction, Low Airflow, Low Charge! Check the Charge!
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- Опубликовано: 30 сен 2024
- In this HVAC Training Video, I Show How to Diagnose a Liquid Line Restriction, Low Indoor Airflow, or Low Charge by Measuring the Refrigerant Charge on a Manifold Gauge Set. I Show the Indicators for Pressures, Sat Temps, Superheat, and Subcooling. You Don't Need to Add Refrigerant to Try to Raise the Vapor Pressure Sat Temp. Simply use These Indicators for Troubleshooting! Supervision is needed by a licensed HVACR Tech while performing tasks as Experience and Apprenticeship garners Wisdom and Safety.
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⚠️ Disclaimer:
Information in this video is intended for educational purposes only. Any work related to the topics in this video should be performed by licensed technicians or by apprentices under the supervision of licensed technicians. AC Service Tech LLC is not responsible for any possible damages or injuries caused by the use or misuse of any information provided.
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Thank you for using digital gauges on this video. Even though I can read analog ones, seeing the actual numbers and changes while you’re explaining makes it soooo much easier to understand and read. I hope you can use the digital ones more on your training videos like this
These days, for hvacr every gauge should be digital. They're more accurate as long as it's a good brand, some people have bad eyes and can't see their gauges also lol. Don't laugh I've witnessed it from a couple different techs. Digital
Does anyone know if I can use this Amazon part number B09NFGZ6M8? I can't afford the $530 digital set. Thank you.
Can I use this same method if it has a piston instead of a TXV?
I've been a tech for 34 years and I think your videos are fantastic. I put together an HVAC tech book for my technicians on how to do all types of troubleshooting and the technicians love having them. I know how much time and effort I put into my book and can appreciate how much time you spend doing these videos. I came across your RUclips channel and sent all my technicians the link to check out your videos and they really love them too. I just want to say thank you for making the industry better.
Thank you so much! Make sure to check out our book and 1,000 question workbokk and also the free articles, quizzes, calcs at www.acservicetech.com thanks!
I can't afford a $530 manifold gauge set . :( Can I use this Amazon manual gauge instead. Here is the search part number B09NFGZ6M8.
Any interest in selling a copy of your book?
do you mind sending me that book you have?
Awesome video!! I brag about you to all the new techs I train how much you helped me start a new and better career. Keep up the great work!
Thats so awesome and encouraging brother. thanks!
I'd love to see you do this on a system with a piston. Thanks for using digital. Probes are the future!
Sure are! I use digital probes on service calls. i just use compound for teaching because thats what the tech schools use, thanks!
Charge to superheat on piston systems.
@@acservicetechchannel how do you like using probes on micro channels
Like how do you use probes on a micro channel wouldnt u mess up your charge connecting a probe to a micro channel?
Please don’t feed the troll.
Thanks for all your great videos Craig! I own and operate my own small business and I've learned so much from your videos and workbook over the years. I really appreciate it!
I just have to say this guy is so great. He makes everything in the video so easy to understand. As a young tech this is an enormous asset because what I have found is most people (older techs) don't want to help you or teach you anything, but this guy helps to bridge the gap when I am in doubt. Thank you sir.
Could you do systems with a piston? Great video, thank you for this!
I wished you would have showed the same thing with a fixed metering device. It would be a lot more difficult with that fixed metering device.
I am from Iran and I love the refrigeration cycle and your videos, thank you for making the video 🇮🇷🙏
low super heat is when there is low air flow
I am not an AC service tech. However, I am required to work on them as they are part of a larger system. These videos help me a great deal.
If your not certified at least a cfc 608 epa universal you should or are not legally required to.
Craig as always, excellent lesson. Great quality videography and sound/audio. You set the standard! Quick question regarding LL restriction - once you have eliminated the service valve and the Filter Drier as the cause your are left with the TXV or Strainer Screen. If you put the TXV Bulb in ice water and there is no change in the meter readings, does that rule out the TXV and indicate the Strainer Screen is the culprit? If the Screen is the problem, what are the options to fix this. Thanks.
A liquid line restriction will be indicated by a temperature difference on the liquid line.
Some condenser units will have a dryer internal to the condenser (before the service valve) so check for temperature changes starting at the exit of the condenser coil.
If the strainer screen on the inlet of the TXV is plugged the body of the TXV will feel cold to the touch... hope this helps you in your troubleshooting!
I work at a hospital where they’re using cooling towers and a heat exchanger ( water cooled system ) to reject heat from the super heated vapor leaving the compressor. These Units are also larger, bigger EVAL coils, than your typical residential systems as well. Does any of your methods change for a such a system?
Another interesting diagnostic video!!
Sooo glad I found
A/C service technologies.
Probably one of the best
Content rich programs on U-tube.
Watching you has made me a better HVAC-R
Installation mechanic.
Thanks for all the editing, content,nd informative literature.
Please add Persian subtitles🇮🇷👍
Thank you for your videos! Extremely helpful and grateful for them.
Great video Craig. I have been learning a lot from your videos and workbook.
My system is a central air, 2 ton rheem. I did check my delta T and it's 17 degrees difference, which means i think it's good on freon. But I did use my testo digital gauges and it shows that my SC is 43 degrees. what could be happening ? filter, EV coil and CONDENSER are clean, 90 degrees outside and 76 in side.
Here’s one!
R410a with TXV, cooling mode.
Outdoor ambient DB=87 F
Indoor DB=85 F, indoor WB=71F
Required sub cooling=12
Low side=145PSIG superheat =15
High side=307 sub cooling=3
Compressor amps 6.9
Outdoor ambient and coil temp sensors both ohm at 8.9
Defrost board flashing High Pressure lock out code. The above parameters were reached holding in the contractor for 10 minutes.
Anyone?
Puzzled need help.5t VS furnace 2 stage condenser Txv.CTOA around 15 to 17 Amana calls for low stage subcool and superheat.SC 5-7 SH 7-9.Subcool spot on but SH high.Delta T low at 14.Evap sat 45 Condenser sat 102. 78RA 64 SA.Elect bills through the roof over 500.00 2200sq ft home.Condenser normal evap starved.Whats weird is I'm getting shaking liquid line and can hear the bubbles.Inside condenser is LLFD.No temp across drier but going in to drier is 3/8 coming out to service valve is 5/16 from factory.Is this causing a change of state of liquid causing all my problems?
Man, I really needed to see this done with the digital gauges. This was very helpful.
Thanks again for a very clear and informative video! Your channel and videos are hands down the best on RUclips!
I have been watching your videos for two years and I bought your book, it has been a great help to me thanks because this is free for everyone that wants to learn how all hvac work
I have a question for you.
I know you said be able to diagnose the system before adding any refrigerants.
You mentioned there might be a low airflow, collapsible ducts, restricted metering device, blower speed issues, or restricted filter dryer. Also, you mentioned checking the
filter before adding any refrigerants. Subcool must be between 8-12 degrees. Superheat 8 to 14 degrees. Those are normal ranges.
Let's say for example, I have a superheat of 12 degrees Fahrenheit, which is good.
On the other hand, I have a subcool of 17 degrees, which seems to be higher than normal of 8-12 degrees subcool.
After checking everything you mentioned and finding out everything is normal, are you still going to use your recovery machine and recovery tank to recover all your refrigerants because the subcool is a little high?
Craig I ran into this yesterday replaced TXV and charge was good however the VSAT was at 27 and pressure was low. Coil was clean like brand new not sure what was going on?!
The question is, is this guidance also valid for industrial cooling systems? Cold rooms Freezers
How can it be 93 PSI and be at 60 F? 8:44
I expect low pressure equal low temp
What would the superheat look like during low indoor heat load / low airflow on a piston/orifice . Would it act like just like the txv ?
I am from Iran and I love the refrigeration cycle and your videos, thank you for making the video 🇮🇷🙏
Please add Persian subtitles👏👍🇮🇷🙏
Master, if I may make a very humble suggestion,......change your cover on all your future videos. When I am looking for a video to educate me, I would prefer to see digital, not analog.
Thank you
Example low airflow even with a TXV usually will have low suction pressure low superheat normal subcooling high delta t low amp draw. On your test you had low suction low evap temp normal superheat normal sub cooling . Any time you have a low side heat transfer problem it shows up with low evaporator temp and low superheat. I believe if you would have let the system run in your low air flow condition long enough to stabilize in this condition your superheat would have decreased too. Do yo agree or disagree? I was just saying you did not let unit run long enough in fault condition to stabilize at fault condition. Are my assumptions incorrect? About the low superheat? Please elaborate…
@R P I disagree low airflow will eventually freeze evap and suction line low superheat. At first it will hunt but upon stabilization it will drop.
@R P Thermostatic expansion valves (TXVs) are often misdiagnosed as the root problem in poorly performing air conditioning and heat pump systems. The truth is that two-thirds of TXVs returned show no signs of failure. For this reason, we recommend taking a system-wide approach when troubleshooting. Eliminate all other components as a source of a system’s performance issues before investigating the TXV as the culprit.
Figure 1
Low airflow
Low airflow is one sign that the cooling system is not functioning properly, and it has nothing to do with the TXV.
Figure 1 shows two identical evaporators being fed by a TXV with the evaporator on the left getting adequate airflow while the one on the right has inadequate airflow (note the superheat values and evaporator temperatures). Low airflow can be caused by a dirty or clogged air filter or a malfunctioning fan or blower motor, so be sure to investigate those components as the source of insufficient airflow.
Greetings, when you think you have a liquid line restriction, what is the difference between putting the txv bulb in hot or cold water?
Ran into a call today 4 degree subcool and 4 degrees superheat with a 17 DT any ideas?
Excellent video 🤘⚡️🤘✨✨
Dave, youre awesome man, thanks!!!
🇮🇷🇮🇷🇮🇷🇮🇷
Another excellent video. Thanks Craig for all the helpful insights into reading gauges. It’s like reading a book!!!!
We have all this stuff in our book at www.acservicetech.com thanks!
Can somebody help me out with info on if the low side sat is low super heat is high.
High side sat temp is high and subcool is high?
Thank you
what about restriction problem without a txv
how do you personally measure the CFM in a system prior to troubleshooting?
How do you like those Hilmor hoses? I had an issue with not being able to remove the depressors.
*Mrs Charlotte is legit and her method works like magic I keep on earning every single week with her new strategies *
these ads musttt stop🤦🏽♂️
Great video CRAIG i was waiting for these video with these type of digital manifold👍👌
Glad you liked it!!! Thanks!
Condenser of chiller has water in it, what kind of chemical can I clean it with?
Anderson Margaret Williams Anna Moore Helen
Always doing a great job ! Thanks for your knowledge ☺️
It will be a greath experience to have a chance to take a personal training with him. It one of my dreams, and im sure one day i will do it...
Do this with Super heat method, Piston. Pleaseee
I just bought your book sir. Thank you for your videos.
Awesome, please let me know what you think of it after reading, thanks!!!
Thank u from Holland
Excellent tutorial. Very clear 👍.
So I just moved and I put my gauges on unit and low side - 64.1psi, 30SH, and 36.9vsat. High side - 243psi, 24.7SC and 115LSAT. T1(67) T2(90). Does this seem to be a TXV issue or dirty coils?
Awesome video by the way! 👍🏾
No one at tire places or dealerships put gauges ona flat tire..you gotta see or find the problem first then put on gauges...what im trying to say is start by checking air filter evap coil condition
Ductboard/sheet metal/attic/crawl space air handler blower speeds then work your way to the outside of the home by checking drainage and condenser coil condition
Craig, have you ever diagnosed a home refrigerator that has cooling problems? I’d love to see diagnosis on that.
What’s going on with it and brand
@@chrisacevedo7683 LG refrigerator...had compressor replaced, ran good for 2 weeks and noticed freezer was at like 10-15 degrees and was not making ice...had tech come back and he added freon saying it was low...ran fine for about a week and again with freezer being in the teen degrees area...refrigerator section, french door refrigerator, was cool...I'm assuming there was a leak somewhere, maybe in evap coil...it was under warranty and we just ordered new fridge...right now it sits in my kitchen inside temp at 80 degrees...just use it for water until new fridge comes by end of month...what would the low side on the gauge read if it were running normal?
My unit doesn't have the subcool value on the plate. It, instead, reads R410A 0.55lbs (I assume this is just the air handler amount), Design Pressure High 550 PSIG, Design Pressure Low 240 PSIG and the unit has a TXV in the air handler and an EEV in the condenser. The condenser has the same PSIG values printed on it as well. My air handler shows 1000 CFM too. How would I determine the sub-cool and super heat from these numbers - is it a simple matter of looking at the saturation temps associated with the PSIG range from R410A p/t chart? Meaning at 240 PSIG, I would have 81F saturation temp and 550 PSIG would be 142F sat temp.?
Look up the condenser Manual and it’ll be in there
I didn't like my experience with it's sman pressure gauge. they are good when the valves don't leak. my second has the same problem as my first Sman460. it is leaking on 2 service valves which has distorted my service calls for a week. Leaked after 1 year both. you don't have this problem? Sorry for my poor english
Great job, thank you very well explained.. Would love to see indicators on leaking compressor valve, stuck open expansion valve.
What bout in a package Unit it the same way
I had a problem today on a 410a heat pump system. It was a new install and I was doing the start up. I dialed in the charge per the charging chart in the unit. I had 332 head pressure 100 suc pressure when it was running in heating mode. But when I put the system in cooling, keep in mind my outdoor ambient temp where I am is 45/50 degrees right now. My indoor return temp was 70/75 degrees. Its a 3 tons system with a piston inside and a txv outside. My head pressure was 175 with a subcool of 5.6 to 8° my suction was 100.3 to 108 but whats weird is my superheat would bounce around from like 8 degrees down to -0.8 and back and fourth my suc saturation was going between 36 down to 30° back and fourth. I know my charge is right. Because I dialed it in according to the charging chart. And the old system was a 3 ton as well. Is this a low ambient issue or a low airflow problem. What's confusing me is my charge looks weird but my air temps coming off the system look pretty good. Heating was 73 degree return. And a 110 degree supply. My cooling temps were 73 75 ish return, 50 52 degree supply. Any ideas would be cool! Thank you.
I love this video. A high Delta t indicates a restricted air flow to the evaporator as well. For those who don't know, the Delta t is the difference in temperature between the return air temperature and the supply air temperature. Normally, it's between 18°-22° Fahrenheit.
My outdoor unit runs for about 2 minutes and then makes a loud knocking noise (like a car thats thrown a rod), and shuts off. During those 2 minutes, cold air does blow. Is that a bad compressor?
Could be. But I've heard some really bad sounding compressors that still work fine.
I normally always see SH around 5 with normal SC in northwest Florida. All the perfect scenario videos I see I have 8 to 15° SH
Why do we have a lower SH?
Also see low SH and Low SC. ??
Another help to show lack of airflow which if you look close at the video. Your suction line temperature also drops. If you have s suction line temperature lower than, say 50-55F you have airflow issues.
the best channel on RUclips, I learned alot from you guys. small question please, you're using F as temp measurement. if I use C , just convert from F to C or what?
Great video thanks I definitely understand things much better 👍👍
This guy is good at presenting and for the most part teaching. But a lot of the time he doesn’t explain things . Almost like he assumes that the people watching know 100 percent of his points I don’t know. Something
Not really a beginner video, he probably assumes you have some previous knowledge.
Thanks for your videos im learning so much, God bless you and your family.
Wouldnt a restriction on the liquid line show a high pressure on the liquid line along with a low suction pressure?
Can you make a video how to flush the lines correctly as well or if it is needed to do it if the old refrigerant is R22 and the new one is R410A, thank you.
As always I like your videos I work hard to become service technician
Watching your old videos to now is a literal jarring, I don't know what it is but you sound much more comfortable on camera now compared to your videos from 5 years ago.
Thank you, this was very helpful
Thanks for all your great videos !I really appreciate it! I´m a begginer in air confitionning but youre a great techaer thank you so much!
It's fun when you get all three at once dirty filter, with a liquid line restriction that someone over charged
You are the best
I just ordered this E book it hasn’t downloaded although I tried it said it had 4 downloads now it’s saying one
Make sure to email info@acservicetech.com with your name, order number, and description of the problem they can help determine whats going on and help, thanks!
Yo I love this channel. This guy has so much good information.
you the best man
You're always coming out with the bangers!
Does this troubleshooting method work for piston systems?
Hi Craig, great video as many others said! My case is R410a system, normal superheat 15, vapor line pressure 125psi, liquid line pressure 315 psi, but my liquid line temperature is 99F! Almost 0 subcooling! I just recharged 3 lb refrigerant, can you help me to understand what’s wrong? Thanks!
May I ask what you found to be the problem?
excellent video...really helps people with their system
Hey can you make a video on the use of dielectric grease when wiring?
I was looking for this troubleshooting information
Is the system is going to attack the same way if you a piston as a meeting device?
Excellent video thank you sir
Good teching session Craig! Thank you Sir.
ABC’s!!!
HVAC
Great job, thank you brother. You are so talented
I really like it another nice video thanks
Brilliant video!👌♥️♥️♥️
Thank u from 🇭🇰 Hong Kong
Very good video great information
Great video thanks 👍👍
👍🤘🤙
Very good info for AC techs
👍
Thank you for another great lesson!
Great video!! Thanks for sharing I'm learning alot from u
Thanks for watching!
The suction line temperature is quite helpful, it nosedived in the low airflow scenario and climbed quite a bit on the restricted. You definitely mentioned it in the video, just bears repeating imo
Awesome that you notice those details, thanks!!!