Fitmiss

I though my problem had to do with the new thermostat I installed but have now realized that the thermostat is working fine. Heat is coming out of the vents however I now realized that no hot air is ever being forced out of the vents thus the house is never reaching the setpoint temperature.

I have made an appt. for someone to do a pre-season tune-up on the furnace and know they will ultimately diagnose the problem. In the interim, are there any suggestions as to what I can do to definitively diagnose and/or fix the problem?

Heat is coming out of the vents. I've heard the fan work and have seen the flame light.

I did notice that I have 4 flashing lights which has to do with the high limit. I'm guessing the thermostat is working too hard to reach the setpoint temperature.

Anyone? Oh - if it is the blower motor, how much should I expect to pay for the repair?

kok328

It just might be the blower motor but, the furnace would only run long enough before it trips the high limit switch. If it is the blower motor, you can expect to pay somewhere in the neighborhood of $250 for the motor, not including labor.

Fitmiss

Is there possibly a fuse or breaker right on the unit that could have tripped? I've checked the main breaker box and the breaker for the unit is fine.

paul52446m

If you lose you 24 volt power at the furnace, there is, on most electronic boards, a small plug in fuse like you use in a car, probably 3 amp. Paul

Fitmiss

Where is this fuse located - anyone know? I'll also have a look on the schema.

kok328

The fuse is located on the green circuit board. It's the blade style fuse used in automotive applications. However, I doubt the fuse is bad because your furnace is able to fire up to the point that heat is not being removed from the heat exchanger which in turn will cause the high-limit switch to shut down the furnace to prevent a melt-down.

seawood

When was the last you replaced the air filters if they are pluged you will not have athe right of return air and will trip high limit and if it trips often it will stay open

Fitmiss

I replaced the filter this week. Is there only 1?

I had seen the 4 blinking lights and read on line that it was sometimes due to a dirty filter. Sure enough the filter was dirty so replaced it and the 4 flashing lights changed to a normal pattern. Still I did not get the forced air and then the 4 flashing lights started again.

The worst symptom is no forced air so the house temperature never reaches setpoint.

seawood

when the light is blinking 4 times is the main blower running is there forced air comming from vents if not it could be the control board or the blower motor you would need to test the blower motor by by passing the control board

Fitmiss

The whole problem is there is no forced air coming through the vents. There is heat coming through but not forced air.