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HVACguy, HVAC Technician
Category: HVAC
Satisfied Customers: 17
Experience:  I have 28 years experience in installation ,service, and design.
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Furnace shuts off before reaching set temperature on thermostat

Customer Question

The furnace shuts down too early. The thermostat is still calling for heat. Furnace shuts down before the temperature desired is reached - later it restarts - and furnace lights - runs for a while - then shuts down after a while. Furnace starts immediately if I turn it off at the breaker switch, but then repeats the process.
Submitted: 8 years ago.
Category: HVAC
Expert:  Rick Mather replied 8 years ago.
This a warm air furnace it might be going off on high limit because of poor air flow check the air filter
Customer: replied 8 years ago.

The air fiter was replaced recently. The old filter was not very dirty. This condo & furnace are only six (6) months old.

Expert:  Rick Mather replied 8 years ago.
Sounds like your furnace is going off on the high limit setting. Check the fan and limit settings you might be able to turn that setting up a few degrees
Customer: replied 8 years ago.

How do I identify these parts - then - I look for an adjustable setting?

Expert:  Rick Mather replied 8 years ago.

Should be small little control with silver cover maybe 2 x 3" has dial inside with three pins attached to there temperature settings lowest is fan off next is fan on and the highest is high limit.

http://customer.honeywell.com/techlit/pdf/95c-00000s/95C-10617B.pdf

Might look like this one.

Customer: replied 8 years ago.

I've removed a couple of panels exposing the electronics - and I don't see any components like the one in the PDF.

There's a nickle sized component located near the gas burner area. Two wires connect to it. Could this part be defective causing the burner to shut down too early? I guess I'm at the point of calling the repair person.

Expert:  HVACguy replied 8 years ago.
you say condo and furnace is only six months old, are you getting air out of the vents, i don't know where you are but here it is code to have fire dampers in the supply duct right at ceiling level, good luck
HVACguy, HVAC Technician
Category: HVAC
Satisfied Customers: 17
Experience: I have 28 years experience in installation ,service, and design.
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