Blower motor in old bryant furnace runs constantly
 

the other day i went into an apartment to do a "turn over" and noticed the furnace service switch was off. i turned it on and the blower kicked on immediately. so i went over to the thermostat and it was in the off position. fan in the auto position. then after noticing the blower running i noticed the condenser is turning on as well. i changed the thermostat and that wasnt the problem. so i thought ok it might be the board. changed the board the next day. same thing happens. when i disconnect the high speed wire for the blower from the board the blower motor hums and the condenser still comes on. the furnace is a 1988 bryant 70 %. any ideas? besides throwing it off a tall building.

Get your meter out, and check for shorts in the low voltage wiring.

refresh