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whity

@insightbb.com

furnace fan blowing constantly

The fan is running constantly yet only blowing cold air, I have a honeywell digital thermostat, I have cycled it, I have lowered the heat requirement and I have just straight turned it off but nothing seems to work to turn off the fan and resume normal heating please help and please don't lock this as I have no way of uploading a picture, thank you very much for any assistance anyone offers it's just that its really cold outside and the heat is going down at an alarming rate


Pacrat
Old and Cranky
Premium,MVM
join:2001-03-10
Cortland, OH
kudos:2
Reviews:
·Time Warner Cable
I have a manual setting for fan speed that allows for a constant airflow... even between heating cycles. It sounds to me that you may have inadvertantly manually set your fan to do the same thing. Normally, if the furnace doesn't light, the fan will not operate for more than a few minutes, before it kicks off. You might try cycling the furnace power off for a few minutes and then restoring power. Double check your thermostat settings, cycle the furnace power, and be ready to call an HVAC technician to look at it.
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jack b
Gone Fishing
Premium,MVM
join:2000-09-08
Cape Cod
kudos:1
reply to whity
Typically this happens if the thermostat fan control setting has been switched from AUTO to manual/ON.

Or, a high-limit safety inside the furnace has opened and it either needs to be reset or replaced, after determining WHY it operated in the first place.

Giving us the make and model#'s of your furnace and thermostat might help...
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HarryH3
Premium
join:2005-02-21
kudos:3
Reviews:
·Suddenlink
reply to whity
Check to see if there is a flashing LED somewhere in the furnace (there's usually a clear plastic peephole to peer through). If the flame detector circuit thinks that there is still a flame after the flame has gone out then it will keep the blower and exhaust fans running constantly, to keep the heat exchanger from getting too hot.

keno5net

join:2002-01-05
Milwaukee, WI
reply to whity
Depending on the age of your furnace this could be a temperature switch in the hot air duct above the heat exchanger. In older furnaces the switch would keep the fan running after the burner shut off until the temperature in the furnace vent cooled down. If it is bad or stuck it could keep the fan running after the system has cooled off.

robbin
Premium,MVM
join:2000-09-21
Leander, TX
kudos:1
reply to whity
I have a digital thermostat that does this when the batteries get low.