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  1. #1
    Join Date
    May 2019
    Location
    Spartanburg, SC
    Posts
    9
    Post Likes

    Carrier locking out only when im not around

    Hey there. I have a carrier split heat pump my company installed in 18 that has locked out twice on me and I believe it has hassled some of our other service techs. It has a "comfort alert commercial diagnostic module" made by Emerson which is what was locking me out on a short cycle fault, and a low ambient high pressure switch for the CFM. Complaint was it wouldn't cool. First time I came out I found only 22v control voltage and install had the unit on the 230v tap of the control trans instead of 208. So I moved it. Voltage went to almost 27v and when I turned it on (and reset the module) everything came on and cycled properly. I let it satisfy. Then cycled it again and no more issues showed themselves.

    I returned today on a recall for the same condition and found the same thing. This time around I went farther.
    I checked charge
    Comp. Discharge was at 146 with 48 ambient in heat, but that seems about right
    This time I cycled the unit many times and switch it in and out of heat and cool.
    Interestingly and the only thing I could suspect is possibly a slight overcharge OR It has
    A Honeywell 5k 2h2c. It's set up for 1h1c and just brings both stages of heat at once. Defrost, strip heat, Y in heat, and reversing valve is controlled by the defrost board in the outdoor unit, it simply receives a W1 and 2 signal, and then runs the heat pump itself. But the thermostat is set up to run a furnace with no delay, could this cause a short cycle to be seen by the module? The module manual says intermittent thermostat signal could fault it. The diagnostic module has a 3min compressor delay built in.

  2. #2
    Join Date
    May 2019
    Location
    Spartanburg, SC
    Posts
    9
    Post Likes
    Thread Starter
    Pretty sure I got it. Under specific circumstances my Low ambient control is shutting off my condenser fans in heating mode. And because they have both stages of heat wired together they don't notice the failure in heating because the strips compensate.

  3. #3
    Join Date
    May 2018
    Location
    VA/DC
    Posts
    284
    Post Likes
    the head master control should have a heat mode bypass relay.
    And set that stat up correctly

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