Search results for query: blend door

Post a pic, its a square kind of plastic box, mounted ontop of the heater box. The blend door rod is verticle,

I haven't been able to find the servo.. I've found something that might be it,

Look at the pic in post#4. Follow the cable from the heater control to the heater box. I belive the cable is moving the blend door. Now as you have an ATC system, there is an elecric servo that controls the blend door.

it switches back and forth between vent/def/floor ok, it's the temperature that isn't working right. not finding much information about the operation either, there's a vacuum operated valve inline with the heater core, hmmm, maybe that is suppossed to only be opened or closed.. a sticking door...

Wish I could be more helpful but I don't know this area that well. What I have learned is supposedly the blend door is electric. And from my own experience with my Fifth if I switch between heat and defrost there's a delay and then I hear the windshield vents open up. So I'm figuring that's...

According to my 86 FSM there is a cable controlled blend door for the heat. As seen in the pic....

...are random. usually low, but sometimes 120*+. the Haynes manual wasn't too helpful. It shows a "typical" later model hvac unit with a blend door, and a temperature control cable next to the fan. I got under the dash and didn't see anything like that. I could see one servo with vacuum...

...it was 50* out. switch a/c on and it drops back down a bit to about 60 ish, turn max on and it's in the sub 40s again. I'm thinking the blend door is gummed up like so many other things on this car and sticking. 2 questions, 1st is it vacuum operated, and 2nd do you have to take the dash...

Bad ballast resistor and your vacuum line running into the interior is either broken/leaking or disconnected somewhere. Both the water valve and the blend-air door operate from that vacuum line. It should be hard plastic with rubber boots, and I'd suggest looking first behind the heater...