Question: Furnace (heater) stops working, resets and works again?

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Answer #1:

The motor cycling on and off is the combustion blower which is the first component to come on. It is designed to blow air into the vent to make sure it is clear when the furnace ignites. There is a pressure switch or two in the vent that will close and allow the furnace sequence to continue if the vent is clear. It stops because the switches aren't closing. The signal from the t-stat is still going to the blower so it tries again until the system locks out as it is designed to do.
To test it, make sure there is no obstruction in the vent from the furnace to the roof. Also, there are small rubber hoses that connect the switches and the blower. They can be removed and cleaned out and put back. Then retry. There should be a diagnostic light blinking and pausing. Look on the inside of the service panel to find out what the light means.

Answer #2:

FLAME SENSOR NEED CLEANED!





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