Page 3 of 4 FirstFirst 1234 LastLast
Results 27 to 39 of 50
  1. #27
    Join Date
    Feb 2006
    Location
    Phoenix,AZ
    Posts
    3,672
    Post Likes
    Quote Originally Posted by Achso017 View Post
    The only thing between the compressor outlet and the service port in heat mode is the muffler and the reversing valve. If it was the muffler I’d have had no pressure on either cool or heat. I haven’t seen a RV cause a pumpdown before either, but what else could it have been? I also saw hot discharge gas bleeding into the suction pipes through the FLIR camera.
    Hot gas bleeding in suction causes high suction pressure never a pump down situation and if that discharge line was blocked. The pressure relief valve in the compressor would have opened almost immediately.

  2. #28
    Join Date
    Aug 2018
    Location
    Piedmont Triad, NC
    Posts
    659
    Post Likes
    Thread Starter
    And I had high suction pressure. In cooling mode it was ~110. In heat is when it pumped down. I don’t how long it would have run or how low it would have gotten as I jumped it back to cooling when the pressures dropped to around 25. Seriously, what else could it be? I honestly want to know for next time.

  3. #29
    Join Date
    May 2014
    Location
    Bay Area California
    Posts
    25,337
    Post Likes
    A heat pump pumping down in heat mode would indicate a restriction at the metering device in the outdoor unit. Maybe even the check valve at the indoor unit. Have to grab the line and see where it was/is getting cold; at least that's the first thing you do before breaking out other tools.
    If you were a real tech, you'd solder a relay on that board and call it good to go.

    I do a triple evac with nitro to remove non condensables.

    I use 56% silver on everything except steel.

    Did you really need the " If you were a real tech " ??

  4. #30
    Join Date
    Aug 2018
    Location
    Piedmont Triad, NC
    Posts
    659
    Post Likes
    Thread Starter
    If I had pressure on the discharge port (suction port in cooling mode) I would totally agree. I had the system losing pressure on all 3 ports. The only thing that makes sense to me is that refrigerant was stacking up in the discharge line before the reversing valve. The pipes on the bottom of the valve were slightly larger than the top pipe, so if the valve carrier was not fully traveling than the larger pipes would have a slight opening back to the suction port but the smaller pipe on top would be blocked.

  5. #31
    Join Date
    May 2014
    Location
    Bay Area California
    Posts
    25,337
    Post Likes
    As I think someone recently mentioned, if that were the case, the head would have shot up and the internal compressor bypass would've started making a hissing sound. Keep in mind, the amount of piping from the compressor discharge to the reversing valve is very small.


    Quote Originally Posted by Achso017 View Post
    If I had pressure on the discharge port (suction port in cooling mode) I would totally agree. I had the system losing pressure on all 3 ports. The only thing that makes sense to me is that refrigerant was stacking up in the discharge line before the reversing valve. The pipes on the bottom of the valve were slightly larger than the top pipe, so if the valve carrier was not fully traveling than the larger pipes would have a slight opening back to the suction port but the smaller pipe on top would be blocked.
    If you were a real tech, you'd solder a relay on that board and call it good to go.

    I do a triple evac with nitro to remove non condensables.

    I use 56% silver on everything except steel.

    Did you really need the " If you were a real tech " ??

  6. #32
    Join Date
    Aug 2018
    Location
    Piedmont Triad, NC
    Posts
    659
    Post Likes
    Thread Starter
    I do have a bad compressor now...
    I really don’t know what else it could be. As I said earlier, there is only a muffler and the RV before the discharge service port. I had my gauges on the two normal ports and a wireless probe on the true suction port. All three dropped like rocks.

  7. #33
    Join Date
    Dec 2006
    Location
    Vancouver, B.C.
    Posts
    724
    Post Likes

    That kind of day...

    Quote Originally Posted by Achso017 View Post
    I do have a bad compressor now...
    I really don’t know what else it could be. As I said earlier, there is only a muffler and the RV before the discharge service port. I had my gauges on the two normal ports and a wireless probe on the true suction port. All three dropped like rocks.
    Is it possible you have a plugged strainer in the liquid line? That would back up the refrigerant in the condenser and pump down the liquid line and evaporator. All three of your gauges would drop down as this happened if in cooling mode. Running the compressor like this could also do damage. You may luck out and find the compressor was only tripped off on its thermal overload.

    If I understand your setup correctly, In hearing mode your suction (hot gas line) pressure would go up as it sent hot gas through to the evap coil and not be able to return very easily to the condenser. The true suction would still pump down though as read from your wireless gauge.




    Sent from my iPhone using Tapatalk
    Quickly, I must hurry, for there go my people and I am their leader!

  8. #34
    Join Date
    Aug 2018
    Location
    Piedmont Triad, NC
    Posts
    659
    Post Likes
    Thread Starter
    If I had pressure on the discharge port (what would be the suction port in cooling) than I would say there is a restriction inside the air handler. Strainer, metering device, etc. But I had dripping pressure equal to the dropping pressure on the other ports. All three were pumping down. Nothing was getting past the reversing valve. There is literally a six inch stub of pipe between the RV and the discharge port. No check valves, no strainers, no driers, no crimps, nothing. The compressor has a muffler and the reversing valve. That’s it. If it was the muffler than I would have no pressure I either heat or cool. By process of elimination it has to be the RV. I was desperately searching for any other cause as I really did not want to have to change that valve.

  9. #35
    Join Date
    Feb 2006
    Location
    Phoenix,AZ
    Posts
    3,672
    Post Likes
    Quote Originally Posted by Achso017 View Post
    If I had pressure on the discharge port (what would be the suction port in cooling) than I would say there is a restriction inside the air handler. Strainer, metering device, etc. But I had dripping pressure equal to the dropping pressure on the other ports. All three were pumping down. Nothing was getting past the reversing valve. There is literally a six inch stub of pipe between the RV and the discharge port. No check valves, no strainers, no driers, no crimps, nothing. The compressor has a muffler and the reversing valve. That’s it. If it was the muffler than I would have no pressure I either heat or cool. By process of elimination it has to be the RV. I was desperately searching for any other cause as I really did not want to have to change that valve.
    I guess anythings possible but, I've never seen it. I did have a York that had a LLFD in the discharge line that was plugged and it wouldn't even run. Pressure relief valve opened before the low side even had a chance to drop. What did you find caught in the RV after you pulled it?

  10. #36
    Join Date
    Aug 2018
    Location
    Piedmont Triad, NC
    Posts
    659
    Post Likes
    Thread Starter
    It was a head scratcher for me too. I can’t even check the old valve because it is toast 😆 nice and crispy.

  11. #37
    Join Date
    Dec 2006
    Location
    Vancouver, B.C.
    Posts
    724
    Post Likes
    Sorry, I miss read your previous post, I see you had high suction in cooling and low suction in hearing. That is backwards to what my theory was based on.

    It just seems like such an odd symptom not to inquire about it some more. I've cut open TXV's before and if I understand you correctly then what you are describing isn't easily possible (like you would need to try and push a mouse through it to block it) from what I've seen inside of them. The slider that switches the suction line makes a tight seal against the suction tubes of whatever mode it's in while the hot gas passes through the valve using whatever of the three outlets is remaining. If the valve is stuck mid position or if the seal has failed then you get bypassing. I don't recall any position where it would block the hot gas. The slider (U bend, Bowl... Whatever you want to call the internal part that changes the state from heat to cool) has a gap between the hot gas inlet and the suction U bend (Bowl) or whatever you want to call it. When it changes from heating to cooling it's not sliding overtop of the hot gas inlet, causing a restriction, because it has a rail that it slides on that holds it above the hot gas inlet.

    I hope that's clear. I can try to explain it better if it doesn't paint a good picture.


    Sent from my iPhone using Tapatalk
    Quickly, I must hurry, for there go my people and I am their leader!

  12. #38
    Join Date
    Jun 2018
    Location
    Homosassa FL
    Posts
    44
    Post Likes
    So just the other day, I had to do a reversing valve. All was going well, I cut out the old RV scratched marks in the pipes for proper order and alignment. All was dandy. I live in Florida, and a monsoon opened up in the sky and it was a made rush to seal up the system. Homeowner and I were scrambling to get components out of the mini hurricane.(no weather on radar either) Sun came back out and back to work. Every went smooth...... until I went to start the unit, equal pressures across the board WTH. I am very methodical and knew I had it right, must be a bad compressor. Tossed in a compressor, same damn thing. Equal pressures. Holy hell I thought to myself, I'm the last line of defense, no one to call no one to help. Lil old couple, weekend you know the deal. I followed all my pipework and low and behold my dumb as had RV piping jacked, I don't even know how I got that backwards puzzle to graze in so perfect looking. I had copmressor and condenser outlets switched, talk about a mind f@$k. Been doing this the better part of 15yrs and yup still have those days.....

  13. #39
    Join Date
    Mar 2018
    Posts
    10
    Post Likes
    I have asked that same question more often as I have gotten older. Doing more commercial work has helped though. As far as replacing we started doing on air or water source heat pumps a compressor gets a reversing valve and in a strait ac package unit a compressor gets a txv. For split system compressor the txv gets recommended. That has seemed to help. We been burned to many times. When the parts are under warranty then it gets a little more complicated. If we don't replace the extra parts we at least recommend it so we don't return for free. We have replaced way to many compressors just to go back to do the reversing valve or txv so it's a packaged deal now. Now if the compressor running with those parts that failed we at least recommend the compressor due to possible damage from parts. It at least gets it on our forms so we aren't returning for free.

Page 3 of 4 FirstFirst 1234 LastLast

Posting Permissions

  • You may not post new threads
  • You may not post replies
  • You may not post attachments
  • You may not edit your posts
  •