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Phil
Phil, Mechanical Engineer
Category: HVAC
Satisfied Customers: 5648
Experience:  Retired HVAC/ Electrical & Boiler contractor. Industrial
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I have an old tuck aire furnace. The heat starts, but the

Customer Question

Hi,
I have an old tuck aire furnace. The heat starts, but the fan does not turn on. What should I check?
Submitted: 11 months ago.
Category: HVAC
Expert:  airheatman replied 11 months ago.

Look n burner compartment and tell me if you see a model on furnace.

Customer: replied 11 months ago.
I cannot find a model number. The house was built in 1959.
Expert:  airheatman replied 11 months ago.

Wow this is going to be pretty old. Do you have a meter for checking voltage? My first step would be to find where the fan common and heat speed wire get power and checking to see if we are getting power to the motor.

Customer: replied 11 months ago.
I have a meter. The motor did start for a few moments and then stopped earlier today. Is there a sensor or switch that could be the problem?
Expert:  airheatman replied 11 months ago.

A limit might kill power to burners. The only thing I can think of really if we are losing power is a bad Fan/limit. Most of these old units had a dial type fan limit that rotated around as chamber heated up. Now if that dial was bad and spring back prematurely it might kill blower.

Customer: replied 11 months ago.
any idea where the fan limit would be in the system? There seems to be two bi-metallic switches, one goes to the pilot area and one seems to go to the fan control. The fan control one (maybe) is about 4 inches long. Could this be it?
Customer: replied 11 months ago.
here is another shot of the switch.
Expert:  airheatman replied 11 months ago.

I see you did not have the dial type.So probably not the issue.Can you trace blower wires to see where they get power and lets see if we are losing it there?