I have a 1989 GMC Sierra 2500. within the past few weeks, my heater has started blowing cold air. But, it doesn't constantly blow cold air. It goes back and forth between hot and cold. Does this mean my heater core is bad, or may it be another problem?
I have a 1989 GMC Sierra 2500. within the past few weeks, my heater has started blowing cold air. But, it doesn't constantly blow cold air. It goes back and forth between hot and cold. Does this mean my heater core is bad, or may it be another problem?