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  1. #1
    Join Date
    Nov 2012
    Location
    TN
    Posts
    11

    Confused Coleman heat pump not defrosting

    I have a customer who has a Coleman Model BRHQ0361BB heat pump that wasn't defrosting. I jumped out sensor (it was about 55 od temp)and tried to force into defrost but it wouldn't go. Made a clicking sound like trying to switch, cut out fan for a second or two then back on. I jumped into ac with r to o and it switched fine. On further attempts to jump into defrost nothing happened. Replaced board (ICM303) and sensor and it makes same clicking noise every time i try to jump into defrost. About 40 od temp. Just a little history: I replaced transformer(40va) and capacitor outside during the summer. Dog had chewed thru tstat wire. This is in a mobile home.
    Thanks for any help

  2. #2
    Join Date
    Jul 2010
    Location
    Eastern Kentucky
    Posts
    55
    build a fire around the unit using wood, then your unit wont need to go into defrost

  3. #3
    Join Date
    Jul 2010
    Location
    Eastern Kentucky
    Posts
    55
    its best to get your post count up to 15 then apply for pro membership

  4. #4
    Join Date
    Jul 2010
    Location
    Eastern Kentucky
    Posts
    55
    55 degrees outdoor temp? there should not really be much of a need for unit to go into defrost. did u check charge? subcooling, superheat?

  5. #5
    Join Date
    Nov 2012
    Location
    TN
    Posts
    11
    I had the defrost sensor jumped out as the refrigerant temp was too high to initiate defrost. Suction pressure was about 65. Couldn't check discharge pressure. The schrader valve is pointed directly at 3/8 line/valve. No to s/c or s/h. Unit frozen last week when temp at night below 30. Sorry i didn't follow procedure. Just signed up today.

  6. #6
    Join Date
    Jul 2010
    Location
    Eastern Kentucky
    Posts
    55
    on the defrost board what is the timer set on? 30/60/90? sounds like your leaving your speedup pins shorted for to long since its kicking in and back out

  7. #7
    Join Date
    Nov 2012
    Location
    TN
    Posts
    11
    The old one was set on 30 minutes. Normal around here is 60 minutes, but sometimes isn't often enough on older systems so I put it back on 30 minutes. I always try to release as soon as I can, but it is possible that I was holding speedup pins too long. If I held continuous it would click repeatedly. Have replaced several of these boards in the past and never had trouble forcing defrost. Did have more than one of this board fail after a few days/weeks and would no longer allow cond. fan to come on through the NC terminal. That was about two years ago. Hasn't been very cold at night since I changed it for homeowner to check/notice ice.

  8. #8
    Join Date
    Jan 2004
    Location
    Lancaster PA
    Posts
    67,712
    Disconnect outdoor fan, let coil frost up, then jump test pins.
    Contractor locator map

    How-to-apply-for-Professional

    How many times must one fix something before it is fixed?

  9. #9
    Join Date
    Nov 2012
    Location
    TN
    Posts
    11
    They called this morning and said it was frozen again. I didn't think it was just a problem with testing. I found another thread online where a homeowner had same problem, same model coleman condensor, but issue wasn't resolved in the forum. They just told him to call a different tech. I remember that there was 23.9 volts between r-c at the board. I thought maybe a weak rv coil, but it switched to ac just fine. Or possibly pulling 24 volts too low when switching fan off and rv coil at the same time? I'll probably be going back tomorrow evening. Thanks for your help so far and I'll try unhooking fan when I go to see if it changes anything. So far it's been too warm every time I've checked it and have been jumping sensor.

  10. #10
    Join Date
    Jul 2010
    Location
    Eastern Kentucky
    Posts
    55
    if indoor unit has TXV make sure it is opening when going into defrost. As you well know if your TXV is not opening during defrost the unit will not defrost properly. What kind of refrigerant? R-22

  11. #11
    Join Date
    Nov 2012
    Location
    TN
    Posts
    11
    R-22

  12. #12
    Join Date
    Nov 2011
    Location
    USA
    Posts
    363
    Quote Originally Posted by dbrown4688 View Post
    So far it's been too warm every time I've checked it and have been jumping sensor.
    Disable the outdoor fan, the coil will get cold eventually.

  13. #13
    Join Date
    Nov 2012
    Location
    TN
    Posts
    11
    Will check TXV tomorrow.

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