Trane xb80 TUE080A948L1
It was cold and I took the covers off the furnace. I tried to start the furnace and only the exhaust fan went on. The circuit board showed 4 blinking lights-I jumped the sail switch and the furnace came on and worked The circuit board blinked steady but when temperature was reached the gas shut down the fan kept running. So I jumped the over temp switches and again the fan kept running after the temp was reached. I jumped the sensor on the blower and still the same thing. Now is it the Fan relay sticking or is it the circuit board malfunctioning?