Hello everyone, hopefully someone can help me here before I have to rip the entire dashboard apart to find out what is going on.

My hot air is working intermittently (which poses a bit of a situation since winter is coming soon). When I say intermittently, I mean it will blow hot, then the air will turn cool and freeze me.

Originally I assumed this must be a heater valve getting stuck and diverting the coolant flow away from the heater core, however I found that my 2002 (V6) doesn't have a heater valve. I confirmed this with Ford. Then I assumed the temperature switch on the dash could be going, especially if it is a variable electric type. However the Ford techs I spoke to when trying to get the part say they don't know how the heater works, and don't know what could be causing this situation.

I was wondering if anyone knows how the heat is controlled. Is the temperature selector switch (the middle of the three *****) electrical, which then operates an actuator to open and close a blend door, or is it mechanical, which I think it may be since the parts breakdown shows some kind of cable assembly? Or, is it vacuum actuated?

Any help is appreciated.

Thanks,
Mike

 

It could be the temperature door (it is mechanical) but you should feel / hear that adjusting I would think.

I am more inclined to say you need the coolant system burped. Usually happens when you're repairing something that involves your cooling system.. new thermostat, new hoses, flush..etc. Most cars will require a burping (usually a threaded plug somewhere in the system).. can also be caused by blown head gasket getting combustion gasses into coolant... burping will fix temporarily in that case.

What is ultimately happening is the air is working its way through the system and ending up in the heater core

 

Thanks for the suggestion. I replaced the water pump over the summer, and had to purge the system then because it was overheating (huge bubble I guess). Well I didn't think about that until you mentioned it again, and now I am thinking that a smaller bubble may have got stuck in the heater core and not worked its way out until I turned the heat on for the first time this year (months after I replaced the water pump).

Then, today I got a check engine light, ran the OBD and found a P1895, cylinder temp overheat. Then, as I was driving the car from the store, my temp gauge crept up to about 3/4. I was about to pull over when it started creeping back down. So now I am inclined to think I do have a bubble in there somewhere, and it is just working its way through the system slowly and causing different symptoms.

About to go bleed it again, I'll let you know how it goes... gonna make sure I open the heater full blast this time, didnt think to do it in the summertime.

Thanks for the suggestion

 

Bled the system last night... fixed everything.

Thanks for the suggestion, I bled it back in the summer but didn't open up the heat. Guess I didnt think about it cause it was too hot!