2013



Results 1 to 19 of 19
  1. #1
    Join Date
    Dec 2012
    Location
    usa
    Age
    67
    Posts
    11
    Rep Power
    0

    heat pump compressor run problem


    My experience/knowledge. Tech school with ice machine field experience. Also some commercial refrigeration field and shop expierence. I was a food equipment (mostly restaurant, bakery, deli, meat dept) for several years.

    I am trying to help a neighbor/friend with a problem with a York mod e2rc048s06g. It is an 8 yr old 4 ton r22 heat pump split system.

    On a call for heat there is a 5 min short cycle delay and then the compressor will start but only run for a few seconds. There is no indication of a compressor start problem and was proven later.

    The control board (part # 031-01954-000) has low voltage inputs, defrost t-stat input (55-31), hi pressure switch input (400-300) plus outputs for the cond fan mtr and reversing valve. Finally there is an 'M' terminal that powers the comp contactor coil.

    After I did some reading about the control circuit I determined that I was loseing the 'M' output but not my R to Y input( tested with meter plus indoor fan continues to run). From what I understand about how the board works an open pressure switch or board fault is all that should stop the compressor after it has started. I replaced the board with a known working one (mine) and got the same symptoms. I then tested by putting a jumper on the board pressure switch terminals while having an ohm meter on the switch terminals. The compressor started and continued to run but I saw no indication on my meter that the switch opened even breifely.

    After I had the unit running for awhile I put my gauges on it, but with no heat pump field experience, the results were meaningless other than at no time did the pressure approch anywhere near 400 psi. Also I had a decent split in the house which would indicate there were no charge or reversing valve issues.

    At this point I normally would have condemned the pressure switch and replaced it but this particular switch (part # 025-33305-048) is brazed on which would require either recovering the charge or at least isolating it into the evaporator. I'm reluctant to do either without being positive that the switch is defective.

    Can anybody confirm that I'm on the right track and know a better way of testing the pressure switch other than with a digital ohm meter. Or am I missing something about how that board works.

    The unit is now operating but with safety removed so a quick solution is needed.

    Also, what are your opinions about a braze on pierceing valve with a charged system and an aftermarket screw on pressure switch.

    Thanks for any and all input.



  2. #2
    Join Date
    Aug 2006
    Location
    england
    Age
    40
    Posts
    3,468
    Rep Power
    28

    Re: heat pump compressor run problem

    Sometimes pressure switches get a bit weak, and will switch momentarily with with the pulses of the compressor discharge, (and sometimes they will operate when they should do...)

    I have not used the braze on saddles, i have had success with an imperial eastman pinch off tool (105 FF) to pinch off 1/4 pipe and braze in new switches and then re round the pipe.

    I would spend a bit of time checking the switch is actually faulty, and that the system isn't overcharged or has sticky check or reversing valves etc.

    I hope the guy is a good friend of yours as these sorts of jobs often bite you in the a$$ when things don't work or it goes wrong again months in the future!
    Mostly found in Oxfordshire, UK :)

  3. #3
    Join Date
    Dec 2012
    Location
    usa
    Age
    67
    Posts
    11
    Rep Power
    0

    Re: heat pump compressor run problem

    Thanks for that. The pulse idea sounds good considering the history. He lost a condesor fan motor and no telling how many times it cycled on the switch before he called me and we got the motor replaced. He also lost a compressor a few months after that and I recommended a new condensing unit but he opted to have a service company replace the compressor instead. He had compressor warranty but the labor was outrageous.

    I'm still looking for ideas about how to determine if the switch is weak or bad.

    It seems like the appliance techs use the pinch off tool regulary but the couple of times I tried it I couldn't get a good enough seal to allow welding.

  4. #4
    Join Date
    Dec 2012
    Location
    usa
    Age
    67
    Posts
    11
    Rep Power
    0

    Re: heat pump compressor run problem

    Another thought. If I go with the pulse theory why wouldn't it do it at random times instead of just during start up. At the time I was wondering if there could be a situation within the reversing valve where it wasn't fully seated in the 'heat' mode that could cause a momentary pressure spike. I can't see it on the gauges just like I can't see the switch open with my meter. Does the slide stay put between cycles or can it drift and reseat on start up?

  5. #5
    Join Date
    Oct 2007
    Location
    manchester
    Age
    40
    Posts
    5,469
    Rep Power
    30

    Re: heat pump compressor run problem

    link the hp switch but keep gauges on as close to the hp switch to moniter operating pressure whilst it starts up

  6. #6
    Join Date
    Dec 2007
    Location
    ireland
    Age
    45
    Posts
    168
    Rep Power
    12

    Re: heat pump compressor run problem

    where are you getting 400psi is this on the pressure switch .this transfers to 71c 27bar, doubt if pressure switch would be set to go this high on r22 system more likely set to cut out about 300psi.
    .

  7. #7
    Join Date
    Oct 2007
    Location
    manchester
    Age
    40
    Posts
    5,469
    Rep Power
    30

    Re: heat pump compressor run problem

    if its a York- anything goes!
    Quote Originally Posted by joe-ice View Post
    where are you getting 400psi is this on the pressure switch .this transfers to 71c 27bar, doubt if pressure switch would be set to go this high on r22 system more likely set to cut out about 300psi.
    .

  8. #8
    Join Date
    Dec 2012
    Location
    usa
    Age
    67
    Posts
    11
    Rep Power
    0

    Re: heat pump compressor run problem

    I've done multiple starts while watching the gauges and they always start near equalized and slowly creep to their respective positions. I've noticed some hiccups on the needle which may be the spikes we're looking for but my only access point is where the lines leave to and return from the inside coil and there's a lot of plumbing between there and the hp switch on the discharge tube about 8 inches from the comp. At no time did the needle move more than ten pounds and that was were it was about half way to its highest reading. If I'm getting a spike that is opening a weak or good pressure switch it's only during the first few seconds after start up which is too soon to be building any pressure against the txv. That's why I was thinking the pressure build up might be at the reversing valve. Another poster mentioned the check valve but a piping diagram shows both of the them after the cond and evap coils. At any rate, if I do have a dischage pressure spike I can't detect it with the gauges.

  9. #9
    Join Date
    Dec 2012
    Location
    usa
    Age
    67
    Posts
    11
    Rep Power
    0

    Re: heat pump compressor run problem

    I'm not getting anywhere near 400 psi according to the gauges and the switch definitely cuts out at 400 psi. We need that here in the S AZ desert in cooling mode. Any less causes nusiance tripping. Thats why it's so perplexing to trip a 400 lb switch with out door air at 45 f and indoor air under 70.

  10. #10
    Join Date
    Dec 2007
    Location
    ireland
    Age
    45
    Posts
    168
    Rep Power
    12

    Re: heat pump compressor run problem

    Without giving us the actual pressures your starting at and levelling out at its very hard to even hazard a guess at the cause of your problem.Also some high pressure sensors on various units are not open and close cicuits

  11. #11
    Join Date
    Dec 2007
    Location
    ireland
    Age
    45
    Posts
    168
    Rep Power
    12

    Re: heat pump compressor run problem

    thats a fair point about the ambient temp, we rarely think outside our own climate

  12. #12
    Join Date
    Dec 2012
    Location
    usa
    Age
    67
    Posts
    11
    Rep Power
    0

    Re: heat pump compressor run problem

    I've not given any pressures because the problem occurs within a few seconds of run time before any 'normal' pressures are developed. I can tell you that I compared my readings to his after about 5 minutes of run time and they were identical. My unit is the same as his except mine is 3 1/2 tons and his is 4 ton. Same mfg and installer.

    You said some pressure switches aren't open/close circuits and that intrigues me. If it's some sort of variable resistor or tranducer then my contnuity test is useless. Can you tell me more?

  13. #13
    Join Date
    Jun 2009
    Location
    Lusk , Dublin
    Posts
    1,129
    Rep Power
    16

    Re: heat pump compressor run problem

    Is there a check valve on the discharge line ?? If so is the pressure switch located between the check valve and the discharge port on the compressor??
    If not use a line tap valve to connect a mechanical hp switch to the stub and test operation.If it works you can either leave it like that or reclaim and fit a 1/4 schrader and a tee with a future service connection on one side.
    Cheers
    Stu
    Last edited by stufus; 28-12-2012 at 10:34 PM. Reason: spaz moment
    Tool's ? check ! Condom's ? check !
    If you can't fix it , f*ck it !!!

  14. #14
    Join Date
    Dec 2012
    Location
    usa
    Age
    67
    Posts
    11
    Rep Power
    0

    Re: heat pump compressor run problem

    I didn't really follow all of that but the way its plumbed the hp switch/sensor is on the discharge line between the comp and the reversing valve. Fitting a hp switch anywhere else would not give me true head pressure in both modes. The problem I have is it's not my unit. If it was mine I'd have invested the $45.00 and some time and installed a new switch and we wouldn't be having this discussion. The owner would like some visible proof that the sensor is bad before he'll let me replace it. As it is, I'd still rather be a trouble shooter than a parts changer.

  15. #15
    Join Date
    Oct 2007
    Location
    manchester
    Age
    40
    Posts
    5,469
    Rep Power
    30

    Re: heat pump compressor run problem

    is there a weak coil on the compressor contactor? is the low side pressure anywhere near the lp tripping range?

  16. #16
    Join Date
    Dec 2012
    Location
    usa
    Age
    67
    Posts
    11
    Rep Power
    0

    Re: heat pump compressor run problem

    I have more information on this problem. My friend called out the service company that replaced his compressor and at first the tech said there was an obstruction in the metering device in the air handler but then, without explanation, said the reversing valve was at fault. Needless to say, he has credibility issues.

    In one of my earlier posts I asked if there could be a situation wherein the slider in the valve was not fully seated in the heat position that could cause a momentary high pressure situation. I also asked that once it was fully seated would it move during off cycle and then have to reseat at the next startup?

    The reason I ask is if I force a start passed the initial 3 to 5 seconds the unit works exactly like mine. Same gauge pressures and same splits inside.

    I can imagine a situation where the slider in the valve is out of position at startup but has finished seating itself after more than five seconds of run time but I don't know if that is even mechanically possible. I only have a general knowledge of how a reversing valve works.

    Has anybody seen a case where a bad reversing valve caused the high pressure switch to trip?

  17. #17
    Join Date
    Dec 2012
    Location
    usa
    Age
    67
    Posts
    11
    Rep Power
    0

    Re: heat pump compressor run problem

    For Install Monkey: I replaced the contactor this summer while we were trouble shooting the comp problem due to badly pitted contacts. Doesn't mean the coil isn't weak but it's just a few months old. Also remember that I don't have any problems with start or run if I bypass the hp switch. No low pressure switch on this unit.

  18. #18
    Join Date
    Oct 2007
    Location
    manchester
    Age
    40
    Posts
    5,469
    Rep Power
    30

    Re: heat pump compressor run problem

    if its a new contactor then that's eliminated that idea, some American manufacturers have a delay on start up that the pressure switch will not trip, have you checked for any temperature drop across the liq drier(in/out) was a suction burnout drier fitted near the compressor? if so any temp drop across inlet /outlet ?
    Quote Originally Posted by Don Lee View Post
    For Install Monkey: I replaced the contactor this summer while we were trouble shooting the comp problem due to badly pitted contacts. Doesn't mean the coil isn't weak but it's just a few months old. Also remember that I don't have any problems with start or run if I bypass the hp switch. No low pressure switch on this unit.

  19. #19
    Join Date
    Dec 2012
    Location
    usa
    Age
    67
    Posts
    11
    Rep Power
    0

    Re: heat pump compressor run problem

    OK guys, I'm closing this thread out. I contacted a friend who is an active tech and talked him into getting involved in my problem. On his very first attempt we saw on my meter that the hp switch opened and stayed open for 10 to 12 seconds. I had probably tried at least a dozen times to catch the switch opening and never did. Oh well.

    He also came up with a great idea about how to get an after market switch back in without opening the system.

    I thank everybody who chipped in with advice. It was a good learning experience.

Posting Permissions

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