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  1. #1
    Join Date
    Jan 2011
    Posts
    135

    walk-in freezer periodically popping control fuse

    Well I got a doozy here, have a 2000 sq ft walk-in freezer with 3 systems, one of the systems is popping the 15 amp control fuse on the strip, it was popping every hr or 2 before, I washed out the plugged condenser thinking maybe the condenser circuit was heating up. This stopped the blowing of the fuse every hr to every day, I installed a resettable 15 amp breaker in place of it, and now seems to blow every 4-5 days, no wires are loose or corroded, the control contactor was replaced thinking I had a bad coil. I tried everything I could think of, took it in and out of defrost while having my amp meter on the circuit and never drew above .20, somehow it is popping, system is cooling well. I am attaching the wiring diagram. The defrost clock is new as well, the fuse that blows is F-3, what do you think!
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  2. #2
    Join Date
    Nov 2004
    Location
    up in the hizzy
    Posts
    1,384
    I think the unit is bad, time to buy a new one! call a contractor near you for a quote.

  3. #3
    Join Date
    May 2007
    Location
    maryland, baltimore
    Posts
    135
    water may be dripping on a connection during defrost or fan delay is bad and humidity is shorting out fan motor.

  4. #4
    Join Date
    Feb 2006
    Location
    FL
    Posts
    565
    I had this same problem on a carrier rtu except my fuse was blowing every other week. finally had enough and went through the whole circuit and ended up being the CCH was going bad.

  5. #5
    Join Date
    Jun 2013
    Location
    N. Canada
    Posts
    402
    Zuke19 I only have phone access, no pics. Can you read out the components in the fused control ckt for me. I assume it's line voltage not 24v ?
    None of the suggested fixes so far have anything to do with that ckt, do they?

  6. #6
    Join Date
    Jun 2013
    Location
    NORTHERN
    Posts
    989
    Call a tech for to see if there might be a relay/contactor/ timer-relay glitch down the running way... a slightest stop/start/restart ATTEMPT, can do same..

    just had a bad coil in relay/ccontactor taking out Trane board 3a, sounded like a buzzer.

  7. #7
    Join Date
    Jan 2011
    Posts
    135
    Quote Originally Posted by jvillehvac View Post
    I had this same problem on a carrier rtu except my fuse was blowing every other week. finally had enough and went through the whole circuit and ended up being the CCH was going bad.
    Was your crankcase heater shorted to ground slightly or wires melted together
    Thanks for response

  8. #8
    Join Date
    Feb 2006
    Location
    FL
    Posts
    565
    Quote Originally Posted by zuke19 View Post
    Was your crankcase heater shorted to ground slightly or wires melted together
    Thanks for response
    I guess at the time slightly. It would blow the 3A fuse so i checked from fuse wire to ground and get nothing. This went on for about 2 months or a little longer and it would work like 2 weeks at a time then out of nowhere blow the fuse. I was oncall a couple weeks ago and got their call again. Go out go through same procedure and finally get 1.6 ohms to ground and traced it back to the CCH, no melted wires. its the kind for an 06D.

  9. #9
    Join Date
    Oct 2002
    Posts
    1,315
    I had an intermittant freezer that had perfect pressures. Traced problem to a defrost heater that was sometimes grounding but never blowing fuse. Heater was controled by swith contact on the neutral side of heater, so when it grounded, it would just warm up and made it hard to keep box cold.

  10. #10
    Join Date
    Jul 2011
    Location
    Lehigh Valley, PA
    Posts
    447
    Put your amp meter on the circuit and close the king valve. Let us know what happens.

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