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  1. #1
    Join Date
    May 2014
    Location
    Hampton Roads
    Posts
    138
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    Heat pump freezing in heat mode

    Im gonna be going out behind another tech to look at a heat pump The customer states the unit is frozen in the morning and has sent a picture of it frozen. The previous tech replaced a compressor this summer. Now its wintertime and he changed the defrost sensor but it still being reported that its freezing. The tech wants to replace the defrost board even though he jumped the defrost sensor out and the jumped the timer speed up test pins and it went into defrost. The tech said there seems to be a lot of oil when he connects his gauges.
    I think the excess oil could be causing a restriction. Any ideas?

  2. #2
    Join Date
    Jul 2007
    Location
    Virginia
    Posts
    11,561
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    Quote Originally Posted by Aronsx View Post
    Im gonna be going out behind another tech to look at a heat pump The customer states the unit is frozen in the morning and has sent a picture of it frozen. The previous tech replaced a compressor this summer. Now its wintertime and he changed the defrost sensor but it still being reported that its freezing. The tech wants to replace the defrost board even though he jumped the defrost sensor out and the jumped the timer speed up test pins and it went into defrost. The tech said there seems to be a lot of oil when he connects his gauges.
    I think the excess oil could be causing a restriction. Any ideas?
    Did either of you verify the outdoor fan motor is operating properly?

    Just like an indoor coil in the summer with a bad fan motor, the outdoor coil will freeze quicker in heat mode if the fan or capacitor is bad.

    The defrost cycle may not be able to remove all the ice before it switches back to heat, and the accumulation of ice just gets greater and greater until you have an igloo.

    Do you have the model number of this unit?
    Instead of learning the tricks of the trade, learn the trade.

  3. #3
    Join Date
    Aug 2002
    Location
    Southold, NY
    Posts
    25,542
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    Go there with an open mind. Start the troubleshooting fresh.

  4. #4
    Join Date
    Jan 2014
    Location
    New England
    Posts
    6,261
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    Check downstream of the OD metering device for frost on initial startup in heat mode. I would disconnect OD fan motor, run on heat for a while to hopefully get a good even frost on the coil, simulate a defrost then let the machine terminate by itself to see if it does that and pay attention if the whole coil is defrosting evenly for starters. Doublecheck it’s not shutting off on a LPC or ( loss of charge control ) if it has one.

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