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Matthew, HVAC Technician
Category: HVAC
Satisfied Customers: 2014
Experience:  14 years experience in the HVAC field of service, installation, Manual J & D calculations
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I have hunter thermostat model# 4299b non programable. The

Resolved Question:

I have hunter thermostat model# XXXXX non programable.
The problem is even without the thermostat the system runs
and with gas flame gone the fan still runs non stop?
can you help
Submitted: 6 years ago.
Category: HVAC
Expert:  Matthew replied 6 years ago.
This old horizontal furnace uses a fan limit relay. It is located on the side of your furnace it is a box with a round disc in it with three set points on the slide of the disc. The lowest set point tells the furnace at what temperature in the heat exchanger to shut off the furnace, the 2nd point is the temp at which the furnace will bring on the blower once the burners fire, the third temp is the temp at which it turns off the burners and just runs the fan because it is too hot. I am going to guess that it is stuck and will not let your blower turn off. Go up and give it a nudge and see if the blower doesn't kick off. It will do it again eventually if this works you are going to need a new one or you will constantly be up there doing that.
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