Dr_Zoidberg57
Member
- Joined
- Jan 30, 2010
- Messages
- 12
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Please bear with me as I know little if anything about heaters but am patient when it comes to sorting through a home repair problem, handy with tools and can follow directions.
I have a 25 year old central forced air gas furnace. According to the label inside, it is a Carrier model number 396GAW000075. I first noticed that occasionally after the fan would shut down, following its cool down cycle, about 30 seconds later it would come back on for about a minute and then turn off. Then I discovered, over the last two nights, right after the set-back time on the thermostat, if the heater happened to be on, the fan would continue to run long after the burners shut down. I checked the thermostat and confirmed that the fan was set to "automatic". I feared that I would have to unplug the furnace as the only means to shut off the fan. As a last resort, I over-rode the temperature set on the thermostat and got the burners to light again. This time the fan shut off following the cool down cycle. As yet, I have not noticed the continuous running happen at any other time.
In searching this and other sites for a diagnosis of my situation, it seems that I may have a failing fan limit control switch. If that is the case, none of the answers I looked at described where it would be located on the furnace or what it looks like.
Any assistance would be greatly appreciated.
Gerry
I have a 25 year old central forced air gas furnace. According to the label inside, it is a Carrier model number 396GAW000075. I first noticed that occasionally after the fan would shut down, following its cool down cycle, about 30 seconds later it would come back on for about a minute and then turn off. Then I discovered, over the last two nights, right after the set-back time on the thermostat, if the heater happened to be on, the fan would continue to run long after the burners shut down. I checked the thermostat and confirmed that the fan was set to "automatic". I feared that I would have to unplug the furnace as the only means to shut off the fan. As a last resort, I over-rode the temperature set on the thermostat and got the burners to light again. This time the fan shut off following the cool down cycle. As yet, I have not noticed the continuous running happen at any other time.
In searching this and other sites for a diagnosis of my situation, it seems that I may have a failing fan limit control switch. If that is the case, none of the answers I looked at described where it would be located on the furnace or what it looks like.
Any assistance would be greatly appreciated.
Gerry