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nelsonesp · May 20, 2009, 10:13 PM

5 amp fuce keeps blowin on the contol board in my AC furnace, went Itryed to put the AC on

wmproop · May 21, 2009, 10:03 AM

You have a short somewhere ,check the tstat wires make sure the wires arn`t frayed or touching anywhere, especially from the furnace to the outside ac unit, if nothing maybe take the tstat wires loose from the contactor and try again,, could be a shorted out contactor in ac unit,, let us know what you`ve found

jerro · May 21, 2009, 10:54 AM

Is this the first time you've tried turning it on this year? Sounds like your control board has shorted out. Did you any lightning strikes in your area lately?

nelsonesp · May 21, 2009, 01:31 PM

Originally Posted by wmproop

you have a short somewhere ,check the tstat wires make sure the wires arn`t frayed or touching anywhere,,especialy from the furnace to the outside ac unit,,if nothing maybe take the tstat wires loose from the contactor and try again,,,,could be a shorted out contactor in ac unit,,,,,let us know what you`ve found

Tnx to all , I fix the problem , it was the transform. Million tnks

thePard · May 21, 2009, 05:54 PM

I just had the same problem in an older furnace... with a newer AC unit.
Unfortunately, it doesn't have a fuse on the 24 volt supply that runs the
Compressor contactor (relay)... There is not even a circuit board.
So it burned out the 24 volt transformer/fan relay

There was a funny stink, like shellac burning in the basement.. and the same smell
In the access panel where the burners are located...

I replaced the 24 volt supply/relay and then found out that the AC still did not turn on
From the t-stat... in fact when I turned the control to cool, the furnace fan stopped running because the 24 volts was shorted out by the compressor contactor/relay.

I quickly turned off the cooling switch at the t-stat and went outside to look at the contactor...
The compressor started when I depressed the manual switch on the contactor.

I will be replacing the contactor since that is where the short is located.
Yes, the AC unit is a Goodman and the contactor is a GE part.

A fuse in the 24 volt circuit would have saved me $50 for the fan relay power supply.

I bet this never happens to me again, so I thought I would pass it on