Feel the heater hoses, they BOTH need to be hot, if only one is hot, the heater core is clogged, if both are hot, the temperature blend door inside the plenum(box) is stuck, either from rust on the shaft, or a bad actuator. If both hoses are cold, check your thermostat. If both are hot, have the truck scanned for codes, this will reveal a bad control panel or door actuator.
Friday, February 19th, 2021 AT 7:52 PM
(Merged)