Carrier Furnace model 58STA fan only shuts off for 10 second intervals
My 3 year old Carrier Furnace, model 58STA had a, seemingly, routine cleaning and check recently. Prior to the service call it was running fine. I noticed that after the cleaning the burner would fire up then the blower would come on. The burner stays on for about 5 minutes then shuts down. The blower continues to run for another 10 minutes, shuts off for about 10 seconds then the whole cycle begins again. The original serviceman said it was the circuit board and replaced it. Nothing changed. The fan is still running for 15 minutes with just a 10 second shut down.