Can't Stop The Heat From Coming In, Any Ideas?

[buickrob]

I've noticed when driving that heat is blowing in from under the dash near the console. My blower is not on but the heat is coming through. I figured that the heat control valve went bad and was stuck open allowing hot coolant to go through the heater core but I changed the valve yesterday and no luck. So, think it has something to do with vacuum?

Does the heater control valve open or close when vacuum is applied? Hopefully it opens with vacuum because if that is the case I will just take the line off. The car doesn't go out in winter and I never need the heat. This was real annoying last year but I figured it was the valve until I ruled that out yesterday. I guess I could bypass the heater core if need be but I'd rather not.

Any thoughts would be greatly appreciated.

 

[QUIP'6']

I've noticed when driving that heat is blowing in from under the dash near the console. My blower is not on but the heat is coming through. I figured that the heat control valve went bad and was stuck open allowing hot coolant to go through the heater core but I changed the valve yesterday and no luck. So, think it has something to do with vacuum?

Does the heater control valve open or close when vacuum is applied? Hopefully it opens with vacuum because if that is the case I will just take the line off. The car doesn't go out in winter and I never need the heat. This was real annoying last year but I figured it was the valve until I ruled that out yesterday. I guess I could bypass the heater core if need be but I'd rather not.

Any thoughts would be greatly appreciated.

YES A VACUUM LINE CONNECTS TO THE VALVE

 

[buickrob]

Yes, I realize that a vacuum line connects to the valve, just curious which way it operates. I have the line hooked up but obviously something isn't working.

 

[scottyb]

I'm pretty sure that vacuum applied closes the valve.
Default no vacuum = heat and defrost.

 

[ELLISDALLASWE4]

While you are looking around trying to fix your heat problem, open the glovebox and take the junk out of it and close the box about 1/2 inch and press in on the clip on the left side now let the box all the way down. You should now be able to see the black cable for the heat controls. Check to see that the black clip is still push into the air box and not broken. If it is broken then that is why you have heat all the time. The easy way to fix this is drill two hole in the box so you can lace two zip ties ... then around the cable so you can pull them up snug.... to very close to where they broke... I guess I should take some pics and post this as they will break sooner or later..

 

[buickrob]

Thanks ELLISDALLASWE4, I'll check that out tonight. Pics would be great but I think I know exactly what you mean. That would be great if it was the cause. I don't really feel heat near the glove box though, just at the end of the console, as if it was coming from behind the bottom of the radio.

 

[ELLISDALLASWE4]

That cable controls the HOT-COLD box. So if it is not closed all the way on hot or cold then you get a leak of the wrong air..

 

[buickrob]

Got it, I'll check tonight. Thanks again!

 

[ijames]

Could be the arm on the blendoor like ellis suggested. The cable comes off with a little metal clip, then you can rotate the plastic arm about 90 degrees from the normal position so two ears line up and then you pull it straight up out of the box. Mine broke off right below the ears and the lower part just fell into the box and out of the way. I got a new one at the dealer for about $7 but they may be discontinued by now. If so, I'd hit the upullit junkyards and maybe you can find one not already broken. My heater valve also cracked across the cylinder inside the valve so I had hot water all the time - the vacuum closes the valve so if you pull the hose off you get hot water all the time. Finally, with the glove box open you can barely see the back side of the heater controls - maybe a problem with that end of the blendoor cable or the big vacuum rotary switch.

 

[buickrob]

Thanks guys, I probably would have looked at the actual control unit next but you guys were right. The plastic arm/swivel broke off so the cable was pushing the rod in but not all the way. I pushed the rod in all the way myself so that will stop the heat for now I'm sure but I'd like to fix that arm. I glued it but I'm sure that won't hold. I'll try spinning it and pulling the whole thing out like you suggested James. Even if I could get it out all the way I could pin it and probably melt the plastic back together.

Thanks again guys!

Rob