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-   -   Trane control board fuse blowing (https://www.askmehelpdesk.com/showthread.php?t=225642)

  • Jun 11, 2008, 06:41 AM
    c2sea
    Trane control board fuse blowing
    Help! A/C unit went out last night. Opened inside unit up (Trane XE80) and pulled the 5 amp blade fuse on the control board and saw that it had blown. Replaced the 5 amp fuse, closed the panel, and the blower started. When I went to turn on the A/C, the 5 amp fuse blew again (and again).

    Main fuse box is not tripping, but replaced circuit breaker and 30 amp cartridge fuses in outside fuse box. Also replaced thermostat.

    I can get the fan to work if I put in a new 5 amp blade fuse, and the LED will flash at regular intervals, but when I try to start either the heater or the A/C, it blows the 5 amp fuse every time.

    Is the control board bad? Any other suggestions?

    Thanks
  • Jun 11, 2008, 06:54 AM
    Stratmando
    Sounds like the heater or compressor coil on contactor may be shorted.
    Remove wires from compressor Contactor coil, try Cool, If it doesn't blow, it is that contactor. Can do same test with heater contactor. Also may be thermostat misswired?
  • Jun 11, 2008, 09:53 AM
    esquire1
    Or could be the low voltage wiring from outside of house to condensing unit got chewed up by dog or weedeater. Have seen this many times
  • Jun 11, 2008, 12:52 PM
    c2c
    Thanks - I had to create a new account for some reason since I could not log back in for some reason... anyway, don't think it's the thermostat since it was doing this before I replaced it.

    I have one of those boxes from the energy company which allows them to cycle the a/c on and off during peak conditions. Since posting this morning, I've heard of a few people who have had problems with these - particiulallry since we have had a few wicked electrical storms which may have caused some surges. Is there any way to bypass??

    Stratmando - where is the compressor contactor coil??
  • Jun 11, 2008, 01:20 PM
    Stratmando
    Your Outside unit has a Compressor and a fan, the wiring runs to a compartment for Electrical connections, A qualified person would turn off power, open the cover where wiring from Disconnect goes into unit. You will probably find contactor and maybe a capacitor or 2.
    The Contactor gets 24 volts from thermostat (Green?)other leg of 24 volts is from transformer in Air Handler.
    You would disconnect wires that go to coil, Like Ebaines was saying, it can be anywhere along the control wiring, from the inside unit to the outside unit, and from thermostat to inside unit. Control wiring may be in same conduit as high voltage(If Insulation rating is mantained). Less likely to be physically damaged, I would Visuially check also, especially since it happens on "Heat" AND "Cool"?
    Newer Systems have more than 2 low voltage conductors, and are used for diagnostics.
  • Jun 11, 2008, 03:05 PM
    hvac1000
    Is there any way to bypass

    Not suggested or recommended with out contacting the utility. They might penalize you for the disconnect of there device.
  • Mar 17, 2010, 09:46 AM
    ybperez
    My heating unit turns on, air come out, but heating air, just plain air. There is a red light that comes on and blinks. I had this inspected and I was told all the wires and connections are working properly, it seems that the circuit box or card is either stuck or not reading right. They said this is what not giving the signal for heat to come on. Is the this the control board and circuit box and card bad? And is it more convenient for me to fix this or buy a new one?

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