I have a Carrier central air and furnace(furnace model 58GS050-3), it was built around November, 1985. It has carrier air conditioner indoor cooling coils box model 28AC030-911 laid on top of the furnace. Everything was working until one week ago.

Now with the thermostat off and the fan set to auto. When turn on the power switch to the furnace, the blower motor start and keeps running and won't stop. I then switch thermostat to cool and set a lower temperature than the current room temperature, the outdoor condenser fan will turn on. When the room temperature reaches the set temperature, the outdoor condenser fan will turn off but the blower fan just won't stop. I have to turn off the power switch to the furnace to turn the blower fan off.

The connection wiring between the furnace and thermostat are:

Furnace-----------Thermostat----outdoor condensing unit

C--------------------------------- White wire
Y------------------(yellow)--------Red wire
Gc-----------------G(green)
Gh
R ------------------Rh(Red), Rc
W------------------W(white)

Does anyone know what the problem is? Does anyone has an online instruction manual, schematic or wiring diagram for the furnace model 58GS050-3 ?

I'm going to say the fan/limit switch is defective. This would cause the fan to run all the time. It could also be a defective fan relay. Hard to tell without testing...

I'm gonna say the fan/limit switch is defective. This would cause the fan to run all the time. It could also be a defective fan relay. Hard to tell without testing...


Thanks for your reply, I took out the circuit board #302075-304 today and don't know which one is fan/limit switch. I search through internet and found out I can buy the whole circuit board around $32 plus $7.50 shipping.

More than likely it is not the board.If it was working before and then you recently used the heat then it is probably the one or two relays you have on the heater wall itself, look at them closely and see if they are burnt if replace them I have had several recently and spent a great deal of time diagnosing the issue. Its not the board.

Indoor carrier furnace will not turn on or the fan. What could be wrong? I check the fuse. All is OK.

I replaced my fan limit switch located behind upper panel of the heater front. Easy with two screws and two wire leads to it. But still same symptoms with the fan continuous run without pulling the heater panel off to make the switch stop power to the blower motor/heater. I need help too, any answers would really help. My emal [email protected]