This pump is from about 1993. I have seen it do this before when we lost power for a second and it reversed the pump. However, I recently returned home to hear only a slightly "different" hiss from the A coil than I was used it. I touched the line set and determined the liquid was cold and suction was hot.

So I shut down for a bit and restarted. It is still doing it!! I am really confused now. Could this be the capacitor? Usually a cap start motor will not start with no cap and the pump fires right up and does not sound too bad other than running backwards.

This is a heat pump BUT I cut the reverse valve out myself so I know it no longer exists so no way that could be it.

Help!

UPDATE: I did verify that the run capacitor is perfect. I can find no other issues. I started it direct on the compressor with the contactor and it seems to start perfect and really does not make any loud racket but is still running backwards.

I know yurt will have something to say about this

 

I hope yurt chimes in because as of now, I can find so joy here. I have not put gauges on yet but I can guarantee that a cool liquid line and warm suction ain't right but as I said, I can also guarantee that there are no heat pump guts left so no way it is reversing flow without reversing the pump. The pump also sounds different.

 

I hope yurt chimes in because as of now, I can find so joy here. I have not put gauges on yet but I can guarantee that a cool liquid line and warm suction ain't right but as I said, I can also guarantee that there are no heat pump guts left so no way it is reversing flow without reversing the pump. The pump also sounds different.

I'm sorry I meant Yuri. Darn autocorrect

 

No problem:yes:

In the old country I had small yurt. Now that I am in Canada I am rich man and have big one with vindows.

 

A scroll running backwards won't pump refrigerant.

Is there a liquid line filter drier in the cabinet. if so, it may be restricted, and causing your cool liquid line.

Put gauges on it.

 

We installed an after market filter drier just outside the condenser.

I am not sure how we would get a noticeably warmer suction line though. I understand the thoughts on restriction but that should trip out the pump overload in short order should it not?

Regarding running backwards. I have seen this same thing last summer with a momentary power outage. Sounded odd and verified line set temps were reversed. I stopped the system and restarted, worked fine. This is my basis for thinking it is running in reverse right now. I think it can do it. The pump is older, before they started putting reverse protection in them.

 

Again, a scroll compressor running in reverse will NOT pump and therefore there would not be a pressure differential to provide for the refrigeration cycle to take place.

 

Scrolls can't pump if they run in reverse rotation. Its due to the design of a scroll compressor. Not something they thought of intentionally though. The compressor will just make a grinding noise, as he inner scroll's edge/edges rub against the outer scroll.

Did you leave the metering device in the outdoor unit, when you took out the reversing valve. Something may be restricting it, if you removed the filer drier from inside the cabinet that it can't be restricted.

A restriction won't necessarily shut down the compressor on low pressure, nor the compressors over load real quick.

 

A restriction in the cabinet, or the outdoor units metering device would tend to make the suction line colder then the liquid line. Cause the refrigerant going to the indoor coil has to much flash gas in it. So the vapor warms up/absorbs the heat, instead of the liquid absorbing it and boiling off to vapor, so little to no latent heat exchange in the refrigerant.

 

Near as I can tell, the system make have run an hour or two like this. It has run perfect all summer long. I keep an eye on it being so old. It runs about an 18* dt across the A coil pretty consistently.

I can go along with a restriction since that is possible but it has done this before over a year ago and then just ran perfect.

No, there are no metering devices left in the condenser. I cut the entire thing out and fabbed up new plumbing. Still have the valve.

 

If the scroll is running backwards. Then the liquid line being cooler then the vapor line would be from the gas on the vapor side heating up from the compressor getting hot. The liquid line would be at outdoor temp.

Remember, since you took out the outdoor metering device. If the scroll could pump backwards. The gas/liquid coming back from the indoor coil would still be hot(no metering device to have a pressure change). So the liquid line would not be cool.

 

Gonna need to put on gauge to find out what is really happening.

An old scroll can run backwards because of a weak capacitor, or a weak start winding. Then again, so can a new scroll.

 

Uh, no need for gauges... I starting thinking a bit and if there is any restriction at all between the comp and A coil (filter/drier), that would probably vaporize the liquid line with the suction side sucking on it.

Anyway, went to just test a port on the condenser. there ain't jack squat in that system!! I mean it dumped out quick! It was working earlier this morning. There was no hint of pressure. I am really hoping the A coil is not it but I would think I would smell that 22 in the house, no? I mean refrigerant is pretty obvious in odor. I guess I did hint at some sort of almost burnt wiring smell in the back room but that could have been many things and probably my sniffer on the high and up.

 

Uh, no need for gauges... I starting thinking a bit and if there is any restriction at all between the comp and A coil (filter/drier), that would probably vaporize the liquid line with the suction side sucking on it.

Actually it wouldn't. The evap coil has liquid in most of it while a system is operating normally. Stop the air flow through the evap coil and it fills with liquid while the compressor is still "sucking" on it.

Anyway, went to just test a port on the condenser. there ain't jack squat in that system!! I mean it dumped out quick! It was working earlier this morning. There was no hint of pressure. I am really hoping the A coil is not it but I would think I would smell that 22 in the house, no? I mean refrigerant is pretty obvious in odor. I guess I did hint at some sort of almost burnt wiring smell in the back room but that could have been many things and probably my sniffer on the high and up.

Let us know where you find the leak.

 

WHaaaaaaaaaat?

 

Sounds like a story from the zone.:yes::laughing:

 

I am getting a little frustrated about now... I found the big leak to be the vapor side isolation valve at the condenser. Fix that. sniffed and soaped, no leak. I test filled with about 10-15oz of 134a (not running it) so I could test pressurize and sniff.

It ain;t holding. Drops about 5psi in 15min. Something is still leaking pretty good. I have the front off if the A coil and sniffed and sniffed. I would think with this much leaking, just putting a detector over the A coil would find it. I went down and back over the A coil several times, no dice.

Only place it seems to be hitting is right under the scroll comp. Not a really solid hit though and I need to know for sure.

Any bright ideas to better detect this leak? I cannot imagine the line set leaking. I also do not see any oil mess that I would expect if the scroll is leaking this bad. All that oil sitting down there, I would expect it to dump every drop of oil before pushing refrigerant. ?

 

Need to bring up the pressure with nitrogen.

If the jug of R134A was sitting in a hot location. Then some of that pressure drop may be because the indoor coil is cooler then the area the jug was store in.

 

You think I might be chasing my tail a bit? I put a total of about 16oz in so far. Each time, the pressure goes up and hold at about 15-20psi and gradually drops to zero. I have soaped the pee pee out of that condenser with my bug sprayer and even made a bubble mound around the base of the compressor. I cannot find a single thing leaking!

I felt pretty confident by the size of the leak at the valve that I found my culprit. I wish I could further verify the A coil but I would also think at the rate of pressure drop, I should be able to sniff something. That sniffer goes nuts over about anything and in that confined, still space in the plenum, it should show up?

Maybe I am getting my education in why N is superior for leak detection!

 

If it keeps dropping to 0PSIG. Then you have a leak.

A little R22, and nitrogen at 200 PSIG finds most leaks pretty quickly.

 

I guess I will have to see what I can buy tomorrow for a Nitrogen bottle. I agree, more pressure sounds great to find this leak. I will also add a little more and see if the pressure drops and holds but right now my money is on a leak....

 

It is certainly leaking. After leaving it for a couple hours, there ain't nothing in it. I decided to clamp down the iso valves to at least see which end I need to look. So far the condenser is holding perfect, as I suspected.

Is there such thing as an easy fix in the A coil? I guess I could hope for a problem in the line set but it only touches two things and both are wood studwalls.

 

Best to find the leak, and then decide what needs to be done from there.

 

I agree with that!:thumbsup:

however, I am running out of ideas to find this leak. Now that it is isolated, it is clear that the leak is either in the line set or A coil. Sniffer gets a little excited working over the A coil but not dead on hit. Just cannot get to every little tube in it.

Ideas? Do I need to try and find a different sniffer? I too would like to know where my leak is before tearing anything down. Die might be an idea but I doubt I will be able to see where it is leaking if in the Acoil anyway.

This might be a good time to ask about sealers. Are they a really bad idea? From what I gathered, when they are exposed to air, they harden up. That makes me real nervous but if there is something out there, I might give it a shot if the system is otherwise shot anyway.

 

I agree with that!:thumbsup:

however, I am running out of ideas to find this leak. Now that it is isolated, it is clear that the leak is either in the line set or A coil. Sniffer gets a little excited working over the A coil but not dead on hit. Just cannot get to every little tube in it.

Ideas? Do I need to try and find a different sniffer? I too would like to know where my leak is before tearing anything down. Die might be an idea but I doubt I will be able to see where it is leaking if in the Acoil anyway.

This might be a good time to ask about sealers. Are they a really bad idea? From what I gathered, when they are exposed to air, they harden up. That makes me real nervous but if there is something out there, I might give it a shot if the system is otherwise shot anyway.

What sniffer are u using?

 

This is a Tiff 5500a. Probably not the best on the planet but if I can get right to the leak, it will hit. no problem but it does get several false positives. I usually reset and retest a few times to confirm. With this much leaking, I would think the whole plenum would light up...

 

Found my leak! So frustrating. Of all things, apparently the plumbing in the crawl space leaks just a bit and was dripping right on the liquid line. ate right through it... After all the effort of getting Nitrogen, I found the leak in 2 min. After opening the crawl space, it was very obvious. I would have found it with 134 if I just looked there.

Anyway, patching it up now and will pressure test again but I feel pretty confident we got it this time.