Gas furnace won't shut off

Old 09-26-01, 06:20 AM
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we have a problem and I would like to know if we can fix it ourselves and what it might be.
See when we set the thermostat to like 75 with the heat on it won;t kick off we have to mess with it the thermostat that is to get it off. The AC works fine with kicking on and on for the right temp.
I can't call a expert cause we can't really afford it
Please help
Thanks Jenn
Old 09-26-01, 01:41 PM
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Smile Fan Switch Stuck

Hello JENN79

Without know which type of heating furnace you have, it's location, brand, model, year etc. i have to assume it's a forced warm air furnace. Meaning it blows warm air through ducts and out of registers in the rooms.

Most likely the fan switch is stuck. The fan switch turns the blower fan on when the firebox {heat exchanger} senses and reaches a set temperature.

The fan switch {often referred to as a fan relay} has contact points that open and close to pass electrical current to the fan motor. These contact points wearout and stick together, which keeps the fan {blower motor} running.

To resolve the problem, the fan switch needs to be replaced. To help verify if the switch is defective, when the fan motor fails to turn off about 10 minutes after the burners go out, firmly but gently wrap the fan switch cover or a solid part of the frame of the furnace.

This action should jar the switch enough to turn off the blower fan. If this wrap does turn off the fan, the fan switch is defective and needs to be replaced.

Use CAUTION around the switch. Do not touch any of the wires attached to it. It uses house current to function. Be sure the furnace is unplugged or the electrical current is first turned off to the furnace prior to attempting any repairs.

The only positive proof any part is functioning correctly, is to carefully remove the part or parts you suspect to be the potential culprit, and have the local appliance parts store person test it or check it.

Read the manufacturers online web site for additional product information, problem solving methods, pictorials and schematics. Patronize our online sponsor and in the electric appliances for additional information and online parts sales.

Regards & Good Luck
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