This Call Had Me Stumped | HVAC Service Call
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- Опубликовано: 7 июн 2022
- In this video I run into a situation I had never seen before, well kinda… this was a strange one. Make sure to watch til the end. Thanks for watching!
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The compressor was spinning backwards .
Originally, scroll compressors had an ant i-reverse rotation Mechanical catch built into the mechanism.
That way this would never happen but they removed it years ago I believe for efficiency reasons and now these scroll compressors always do this.
Time delays sometimes help, but if the power blip is less than a half a second, a time delay cannot see this and this ends up happening anyways. It's frustrating.
I believe ICM sells a single phase phase monitor and I believe it has a time delay built into it as well. It's the best thing I've seen out there to help with this problem so far.
We see this problem all the time in Florida.
Customers call all the time saying that the unit's not cooling and the outside unit is making a funny noise. We just tell them to turn the unit off at the thermostat. Wait 5 minutes and turn it back on and everything works great after that.
This happens a lot. When a technician is fooling around with a float switch on the condensate pump or one in the drain pan well the system is running and then this accidentally happens.
Turn the unit off. Wait a minute or two and turn it back on and you'll be good to go.
Have fun out there!
Always good to have a short cycle timer on compressor 24vac contactor control. If not incorporated into unit you should add one in compressor control line. They are not expensive and good insurance.
If you live in a place like Florida, the lightning capital of world, there are a lot of grid glitches that trip a short cycle on compressor.
Copeland says running backward is not damaging but it does overheat compressor causing compressor internal protection breaker to trip. When it resets and starts up compressor again it runs in correct direction. However, too many trips on these compressor protection cutout switches can damage them, requiring a compressor replacement.
BTW, some electronic thermostats claim to have short cycle protection but on some that is only for user tweaking controls reactivating cooling shortly after unit went off. If they do have short cycle protection and installed lacking 24vac return blue 'C' wire, opting to run thermostat on internal battery, there is no complete 24 vac power path from transformer to thermostat to detect a power short cycle glitch.
Appreciate this man trying to absorb as much info as possible. Just finished trade school hoping to get hired soon.
Hope all goes well for you. I hope the channel helps as you continue to learn.
Float switch hooked up on Yellow instead of RED. Will do it all the time. Needs to be on red so the whole system shuts down and then the delay kicks in. If not the compressor will go off and on and start going backwards.. Yep if you don’t see it you will have a hard time figuring it out.
Thanks for this explanation! You are very easy to understand! Thanks!
Maaaan that happened twice to me this week you know checking the float switch on the maintenance and by accident i engaged the switch really fast compressor got louder and it turned off thermal overload i let it cool and unit was working just fine! 😨 And i was struggling because i didn't think was the compressor. Thats why i like to cut the R from the board instead Y to avoid that! Didn't know that make the compressor run backwards sound like it's working but is not doing anything! Thanks for sharing it! 👍👍
This has givin me answers for a couple calls that I was at for hours and left defeated.
I've had this happen to me once or twice. First thing I thought immediately from the sound of it was it was running backwards because the compressor sounding a lil crunchy lol. Good on you for figuring it out man!
we normally add a time delay to prevent this.thanks for sharing.
Has a time delay. A lot of installers hook them up to the yellow only. Contractor just goes off and there is no delay in between yellow to contactor…… RED is the one that the float switch should be breaking on if not it bypasses the delay..
I’m new to service. I thought maybe it was a heat pump and the reversing valve was acting up. Great video! Thanks!
Wow! Didn't know they could run backwards... Interesting!
I like watching hvac video's. But most are the same over and over. This my friend was a great little video of something you don't see everyday. Thanks.
Wow exactly was my 1 st thought compressor running backwards but good find to find an safety switch problem ..ive had a only a few pumps do that over last 25 yrs in the business ive caught them bounce on & off on an pan switch when pan was full of water but that way more obvious , but always good idea to test & to fill an pump with water & make sure it cycles on & off ..Great Job / glad that was all there was
I love your honesty
Great video! Thank you for sharing
Thanks for being humble
Great Catch! Love your vids....thanks
Not sure if I would have checked the TXV first thing.
Thank you for sharing and glad you ended up getting it!
Thanks for sharing this video!
Wow. Who can tell that was the problem. Great info brother. Thanks!
Sometime thunder, bad weather can cause a power surge that causes the compressor to function like that.
Thanks, I did not know that. Weather! Woww! Surges, brown outs? Lighting !
I've never seen that happen Good job! Everyday is a school day
Real life scenario. Thanks!
Nice video figuring that out, thanks for sharing 👍
Great 👍🏻 video like always keep them videos coming
Daaang... That's crazy. Good catch.
Thanks for the golden nuggets
Excellent! 😎👍
I just learned something else to watch out for....thanks guy....hvac on.....
I was already thinking backwards right as you said that safety was bumping. Would've over heated soon and you would've been scratching your head want to know why it was getting hot! GOOD FIND
good explanation
Compressor was running backwards. It happens all the time in Florida with lightning 🌩 and storms
Had a Rheem AC do the exact same thing on me a few months back. New install with a condensate pump and all! I was by AC when it kicked off on me twice… unit made the most horrible noise and when it kicked off compressor ran backwards both times. Found out it was issue with condensate pump
Same happens if you have your run winding on your run cap rather then the start winding. Ive seen new techs do this same mistake. Id still look at it too due to it being new unit. People make mistakes
Good catch great video.
I’ve scene super seal fuck with pressures that haven’t run for a few days(Customers have turned system off) bad cap, replaced started up, head pressure at 290, ran system for 15 minutes, then dropped to normal pressures, SH SC a perfect. Yellow dye and the smell of QuickStart when I took my gauges off.
Usually a power blip but no point in asking as most people don’t notice. I’ve had power blips that did exactly that to compressors but they will usually overheat. The float switch doing it is really unique though. Noisy when they stall. Added a time delay cube so it can’t fast cycle. Problem solved.
good info to know thanks
Thanks buddy
I have definately turn the main power of and back on and get that sound on the compressor. Only once have I ever had the compressor with equal pressures. Adding or removing 410a didn't work. Even replaced TXV. Same problem. And all this was still under warranty.
Wow
Most of the new scroll compressors have an anti reverse mechanism built in. An easy way to check if the thermostatic expansion valve or TXV, I don't do the acronym thing I'm not that lazy yet. Put the system in cooling, let it run for a while and then shut off the condenser fan motor and let it run. Watch the high side pressure don't let it get over 400 psi R 410a. If the valve is working properly the low side pressure should stay the same. That shows that the valve is maintaining the superheat. It will raise a little when the high side pressure gets closer to the 400 psi mark. If the valve starts moving around it's not holding the superheat setting. Just some useless information.
Not useless info! Good tip. Thanks, I’ll use it.
No worries, it happens to the best of us!
Good video man
Thank you 🙏
Didn’t check the filter or the either of the coils as well make sure all the vents re open.
Compressor short cycled. Once reset you were good
I had that exact same thing on a trane unit the other day
Man !!! We are not perfect, that's happened to me one time and you would think the time delay would pick it up !!! But does not
Im kinda new to service and can say ive also experience this. We are paid a certain amount by the job and i was trying my best to figure out what was going on. I turned the unit off to check the caps and when i turned it back on equal pressures i was like what the hell. Can this happen with straight air?
So that means your pump was wired to shut off the a/c only, if it was wired to break R to the digital thermostat the thermostat would go through time delay and that wouldn’t happen.
Trane claims the Nest and Ecobee stats will do that. I keep tdr's on the truck for those.
Years ago mfgs put delay on em, now it’s in the circuit board but if the pump is breaking y it may not make board time out
Add a delay on break timer … used to be 30 second on the mfg timers
What ref? Out door ambient? Seen the SH, but did you measure it? Just currious.
So were they breaking y or r , cuz you would think if they were breaking r why would it not trigger that 5 min delay on the thermostat? If they were breaking Y they're chalked
Next time break red wire thru condensation pump not yellow and use the thermostats time delay to prevent this from happening again
I see two possible causes of the equalized pressure. Yes when you cut the power off and on real quick it can trick fuck the compressor and sound like shit. Based on your pressures I’d have to guess it was cool day and cold nights season. With that being said I’d have to guess it was 60-65ish degrees outside when you were there and about 70 inside. I see an overcharged system that tried to run early in the morning when it was 50-55 degrees outside and caused the plates in the compressor to separate and pressures to equalize. The sub cooling is high for the given outdoor temp and your super heat is on low side… low super heat is either low airflow or overcharged system flooding the evap coil.
Will a time delay switch work ? It would keep the compressor from coming on after a small power surge. By the way good video👍
Beat me to it I was thinking the same thing.
Most thermostat have a time delay built in. Some have installation settings where it can be turned off but if the unit loses power for a fraction of a second it isn’t always registered by a time delay. I had a system where the contactor would flicker really fast after a couple minutes of running and they compressor would start screaming. Every time I checked the system everything looked great. Thought it might have been a bad defrost board intermittently working but it was just a float switch that wasn’t fully seated and the water would lift it just enough where the float made a partial disconnect
Mount a time delay in the condenser for 30 seconds or break the r for the thermostat.. if the drain pump did it once, there’s a good chance it’ll do it again..
Question do they have an SS2 if so it happens all the time here in Florida either the SS2 trips it or the power came and went and the compressor just kind of went out of sync. Usually if you shut it off and turn it back on it'll be fine to remedy this put in a time delay on break
Oh check and flush drain if necessary
Yup wee see it so often. Just enough water to push the float up a little and the compressor will start to run backwards.
Oh I was way off they definitely is a new one
Thank you so much I just got out of trade school last year looking for jobs any tips on being a good tech ?
Be honest
It’s raining you don’t think it had something to do with the pressures?
What did you do to resolve the problems or prevent it from reoccurring? What did you actually do to justify your fee?
Id think he changed the condensate pump,
Yes I did. And we went back and installed a break on make relay
👍
410-A?
Sybscribed!
🤯
Good catch, so no compressor delay time involved with condensate pump interrupt?
Looked like a weak compressor
Put that seatbelt on
Great info. Why aren't you wearing your seat belt?
short cycle timer
That compressor looks bad the valves maybe shot
Scroll compressor, no valves.
A three phase compressor wired incorrectly will run backwards with equalized pressures. Never seen it on a single phase unit.That’s interesting. Good catch.
Take that pump out of the system problem solved.