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no 24 volts

Hi everyone-

  Had a goodman air handler with electric heat coils/evap coil go down.  Wasn't getting any control voltage out of the transformer----208>24 volts.  Had 208 going into the transformer, checked voltage at breakers and all safeties/switches.  Replaced with a brand new transformer and same thing, no 24V coming out of transformer but I noticed the transformer got warm to the touch.  Talked to the tenant on the way out, and he said he recently installed a wall mount TV near the thermostat.  Would a short in the thermostat wire cause the transformer not to give off 24V?  There is no neutral hooked up to this unit, just ground.  When I go back tomorrow, I'm going to disconnect all thermostat wires and see if I get anywhere.  Any other ideas?




  • Techman
    Techman Member Posts: 2,144
    Low volt

     Turn off power,on the 24v side of xformer,remove all wirers, re-power & check for 24v.What VA rating was the original xformer? What is the replacement xformer VA ?
  • Del
    Del Member Posts: 52

    Just like the old one. I determined that the new transformer I put in was fried due to a short in the low voltage line to the condenser. When I put another new one in, I pulled off all the 24v wires from the board and jumped out r-g and the fan started, and I was getting 24v from the transformer. Whenever I hooked the condenser control wires back up, the transformer voltage would drop to 4--5 volts and nothing would

    work. This led me to believe there is a problem either with the condenser contactor, or the 24v wires. This is an older goodman AH and there is no 3A fuse on the board. I checked all the thermostat wires for shorts, none found. Anyone else have any ideas?
  • Techman
    Techman Member Posts: 2,144
    lo low volt

    You should put in a auto style fuse/buss control fuse/ or 24v circuit breaker. It does sound like a stuck contactor.
    RDSTEAM Member Posts: 134
    use a

    xformer with a reset button on it. this way your not constantly replacing formers. disconnect you condenser stat wires and test continuity
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