QuestionQUESTION: My wife has a 95 Caravan, 6cyl. About 140K miles.
Heater won't stay on hot. When idling it blows only cold air in any setting. When the RPMs are up, it will blow hot for a while and then fade to cold. If you move the temp control from hot to cold and back to hot it will then blow hot again for a while before fading to cold.
From the indications it looks like a vacuum controlled hot-cold flapper has a vacuum leak. Assuming so, is this an internal heater problem or could it be something external to the heater?
I note one of the vacuum (?) lines going from the brake vacuum assembly to the heater has a small cylindrical assembly on it. Could that be a filter or regulator that could be bad?
Is there any easy way to access the hot-cold flapper and permanently wire/set it in the hot position? I don't care what the repair does to the dash or heater. We'll be getting rid of the car in six months any way.
ANSWER: check for clogged heater lines or low coolant
---------- FOLLOW-UP ----------
QUESTION: Surely you jest. Did you see the part about VACUUM?
Answerhehe I take it u dont know how engine vacuum works do ya?
When the engine is at high RPM the vac is low thats why there are check valves in place to hold the little vac that is in the system there. Go out to the heater lines and feel them both when the engine is all the way hot if both lines do not feel the same temp then one is clogged inside the heater core.
