I have Goodman GMT090-3B. It is stop running. I have check the control board and there is no indicator light. The power is ok from the breaker. The thermostat stop working since it is power through control board. Is the problem with control board. Do I need to replace it? Please advice. thanks.
check the transformer to see if you have 24 volts supplied at the secondary side, if not you have a bad transformer and that would explain no power to thermostat, reply back and let me know what ya come up with
pull the stat off the subbase and jump R to G if you don't hear the supply fan or see a little spark the TR is shot.if you have a meter set to ohms "audible" and remove the 115V wires and the 24V side and ring them..if you don't hear anything on either or both sides the TR is shot.40/50 VA 115V/24V Grainger or HD,Lowe's