I am having issues with my heater blowing hot. It will work as long as I maintain at least 1,500 RPMs and a decent speed but if it drops then it starts blowing cold air and the engine starts to overheat. I have a feeling it has something to do with the vacuum that controls the heater but not sure if it would be just a line or if it would be the heater control box itself.
With the engine idling and at operating temp, grasp the 2 hoses going through the bulkhead for the heater core. They should be HOT. Check thermostat, make sure it's opening properly. Make sure you can see coolant flowing in the radiator.
January, 14, 2012 AT 1:21 AM
All of that is working properly. It just doesnt want to stay on heat. I just dont know if it would be the selection box or a vacuum line to the box
January, 15, 2012 AT 5:18 AM
Use brake cleaning fluid or carb cleaner to check the vacuum lines for leaks. Make sure the actuators are moving the blend doors properly.