furnace will not shut down

nhuppric

I just replaced the inducer motor on my payne furnace and now the furnace does not shut down after reaching the desired temperature. We did not have this problem before the inducer motor went out. can anyone advise?

beenthere

Did you check to se if a wire got bumped and moved to a position that it is now shorting. And causing the furnace to run.

HoosierJayBee

First double and triple check the motor wiring to make sure everything is correct. It is possible you may have unknowingly bypassed a switch or control wire.

Next, make sure that the limit switch is connected and working properly. This turns off the furnace when the proper room temperature has been achieved.
In my Rheem RGAA furnace, this switch is mounted inside the furnace housing but outside the plenum, about one foot above the fan motor. Make sure it is still connected in circuit. In my furnace, one wire from this switch goes to the 24volt gas valve and the other wire goes to the R8239A transformer/relay module. Once you confirm that the limit switch is still connected in circuit, remove the cover of the limit switch and watch the internal round dial. I have an a.c. power switch mounted on the outside of my furnace housing. I would turn that off to allow the furnace to cool down. You will see the limit switch round dial rotate in one direction. Then turn it back on. As the main burners heat the air, the limit switch round dial will physically rotate in the opposite direction until a certain temperature is reached before turning on the fan motor. This will confirm if the limit switch is working or not.

Affordable7

Could it be that your thermostat went bad also (unlikely timing, but it does happen). To isolate the thermostat and thermostat wiring from the unit go to where the circuit board is in the furnace and take the red wire off the "R" post and push in the door safety button and see if the furnace doesn't run. If not, then you have a bad thermostat or the wiring has shorted somewhere. If it continues to run, and you're sure all your wires are reconnected back the right way after the inducer replacement, you might have a bad circuit board, because the furnace (through the low voltage side) "proves" the safety features of the furnace before it ever activates the high voltage...i.e. inducer vent motor. Good luck.