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BillyHvac, Journeyman HVAC Tech
Category: HVAC
Satisfied Customers: 22629
Experience:  Endorsed for unlimited heating, cooling, oil burners, boilers, refrigeration, hydronics
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Older Carrier HVAC. When heats up to thermostat set temp

Customer Question

Older Carrier HVAC. When heats up to thermostat set temp will shut off and then the fan will come back on for a short time.
JA: Did you double-check the thermostat's settings? And what about the filters?
Customer: Thermostat settings are good as is the filter
JA: Do you plan on doing the work yourself?
Customer: Yes
JA: Anything else we should know to help you best?
Customer: Don't think so
Submitted: 11 months ago.
Category: HVAC
Expert:  BillyHvac replied 11 months ago.


My name is ***** ***** I will do my best to assist you. I am looking over your question now and will respond shortly.

Expert:  BillyHvac replied 11 months ago.

This common with older furnaces with a heat activated blower switch.

As the switch ages it gets weaker..The burners come on, heat the furnace, switch senses heat and kicks on blower. Burner goes off...switch senses when it cools and then shuts the case of an older switch it shuts off and then the warmth still in the furnace activates blower again until cool.

The only true fix is to replace the blower switch.