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  1. #1
    Join Date
    Mar 2007
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    Mesa AZ
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    Default Heat pump shutting off

    Todays inspection the heat pump, on the cooling cycle ran for 30 seconds, then shut off for a few seconds, ran, shut off, after it did this for a few times I shut the unit down. For the time that it ran it was cooling.
    What would cause this?
    I ran the heating cycle first, It didn't do it on the heating cycle, and I don't believe it started shutting down untill the unit was running, on cool for 30 or so min.

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  2. #2

    Default Re: Heat pump shutting off

    Could be the high pressure switch, are you sure the condensing unit came on in the heating mode or could it have been the heat strips providing the heat?

    Clarksville Home Inspection
    JW Goad
    TN License #307 | KY License #2402

  3. #3
    Join Date
    Mar 2007
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    Mesa AZ
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    Default Re: Heat pump shutting off

    Quote Originally Posted by John Goad View Post
    Could be the high pressure switch, are you sure the condensing unit came on in the heating mode or could it have been the heat strips providing the heat?
    No. The unit didn't have heat strips.

    Phoenix AZ Resale Home, Mobile Home, New Home Warranty Inspections. ASHI Certified Inspector #206929 Arizona Certified Inspector # 38440
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  4. #4
    Join Date
    Mar 2007
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    Charlotte NC Licensed in NC and SC
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    597

    Default Re: Heat pump shutting off

    My guess would also be a pressure switch or actual pressure problem but for the DIY, it would be easy to replace the main contactor to see if that is the culprit. These are high failure items, the 28 volt coil could be opening up or the contacts worn. Another common problem is loose connections in the disconnect or at the breaker. Also loose thermostat cable connections or even a flaky t-stat.

    Bruce King, B.A. King Home Inspections, LLC
    www.BAKingHomeInspections.com
    Certified Master Inspector, Independent Inspectorwww.IndependentInspectors.org

  5. #5
    Join Date
    Mar 2007
    Location
    Plano, Texas
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    4,170

    Default Re: Heat pump shutting off

    Not enough information to even begin to know what the problem is.
    What was the outdoor ambient? Indoor ambient?
    My first suspicion would be a low pressure switch, especially if a operating in low temperatures. Could be high pressure if outdoor ambient was high.
    Need more information, but as far as the recommendation, it needs service unless you were operating it outside or near the temp. limit.

    Jim Luttrall
    www.MrInspector.net
    Plano, Texas

  6. #6
    Join Date
    Mar 2007
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    Mesa AZ
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    1,181

    Default Re: Heat pump shutting off

    Quote Originally Posted by Jim Luttrall View Post
    Not enough information to even begin to know what the problem is.
    What was the outdoor ambient? Indoor ambient?
    My first suspicion would be a low pressure switch, especially if a operating in low temperatures. Could be high pressure if outdoor ambient was high.
    Need more information, but as far as the recommendation, it needs service unless you were operating it outside or near the temp. limit.
    Out doors it was apx 70 degrees when I ran the heat.
    Shut it down for apx 30 min. before switching it to cool.
    About 75 in and out when I started it on cooling.

    Phoenix AZ Resale Home, Mobile Home, New Home Warranty Inspections. ASHI Certified Inspector #206929 Arizona Certified Inspector # 38440
    www.inspectaz.com

  7. #7
    Join Date
    Mar 2007
    Location
    Plano, Texas
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    4,170

    Default Re: Heat pump shutting off

    I'm guessing cycling on low pressure switch. I'd be looking for clogged indoor coil/filter first, then proceed to check the refrigerant level, clogged filter dryer, defective metering device, and proceed from there. I assume you checked the filter and maybe looked at the indoor coil.
    Bottom line though is it needs service UNLESS it is a clogged filter.

    Jim Luttrall
    www.MrInspector.net
    Plano, Texas

  8. #8
    Join Date
    Mar 2007
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    Mesa AZ
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    Default Re: Heat pump shutting off

    Yea everything was clean.
    Guess this is another good reason to go around the home a couple times.
    I may not caught it otherwise.

    Phoenix AZ Resale Home, Mobile Home, New Home Warranty Inspections. ASHI Certified Inspector #206929 Arizona Certified Inspector # 38440
    www.inspectaz.com

  9. #9
    Join Date
    Feb 2009
    Location
    Indiana
    Posts
    37

    Default Re: Heat pump shutting off

    Was the entire unit shutting down? Compressor and fan, or just the fan? Could be a low ambient set up with a thermostatic control, cycling the outdoor fan off and on to keep head pressure up. It shouldn't have taken thirty minutes, but as the heat load in the house came down, the system temp, along with the return bend, or coil temp where the temp sensor was located would also drop; possibly to just below the switch setpoint. Its possible the switch was not working properly, or the unit charge was incorrect. Either way, a good service tech should take a look.


  10. #10
    Join Date
    Mar 2008
    Location
    southern ontario
    Posts
    130

    Default Re: Heat pump shutting off

    Hope you have your problem fixed by now but if not Hometips.com, Heat pump troubleshooting, deals with that exact problem.


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