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heater doesnt switch from defrost


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Posted

if u have;t already geussed it i go a problem with my heater...the fan changes speed the temp changes and the ac works but the air only comes out of the defrost vents by the windshield i was wonderin if this is an easty fix or if there is somethin major wrong

Posted

What year? If it's below '93, your vacuum check valve is probably broken or cracked. It's located under the cruise control modulator.

Posted

its a 90...wheres the the cruise controll modulator? what does this little valve look like ?

Posted

It's right behind the airbox, next to the brake booster. There are vacuum lines that run under there. Pull them all up and look for a black plastic joint/valve thing. Most likely it's cracked or broke in some way. $7 dealer part.

Posted

awsome thanks for the help im going to go and check things out later and hopefully it all works

Posted

is it directly below the cruise control..im assumin that the big round thing by the air box with the four black hoses running from it? if it is that then it doesnt look to cracked but i cant really get a good look at it does the air box or cruise control modulator come off easily so i can get a beter look also this black thing was no more than 2 inches maybe 3 inches in length is that the rite thing?

Posted

you may also have a vacuum line off under the dash causing it. Start the car up and listen for a hissing sound or a faint wistle sound. It diffently sounds vacuum line related though.

Posted

checkvalve.jpg

That's what you need to be looking for. That's a picture of my old one, it's broke and missing a whole side of it pretty much.

Posted

awsome thanks thatll make things a LOT easier i was kinda in the dark as tro what it looked like

Posted

well that valve doesnt seem to be the problem i count find any cracks on it or can it be from some very small cracks? would it take that little to cause a leak? ...so now what about these vacum lines? i think i can hear a slight noise but its not very loud and i have no idea where its comin from

Posted

Does your cruise control work? The vaccum source is the back of the plenum. If your cruise no workie, then that line is prolly broke or disconnected

Posted

my cruise works fine it always has ..when i put my hand up by the stering wheel under the dash i can feel a lite breeze when the fan is on high is this normal?

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