This is one of the few areas I haven't worked on yet, so I wanted to ask before I tore into it. Some guy worked on it last year and set the control inside the dash to hot and told me not to touch it - he said there was a door that was broke or something to that effect. Well, guess what - it's burning me up now! What would this be called, and how hard is it to get to? I'm limited on time and don't want the car down for days waiting for me to find time to work on it, while I'm driving the 9-mile-per-gallon 71 GMC. While I'm asking, when I'm driving the vent by my leg in the console (87 GTA) blows out hot air. Shouldn't this vent close when the heater/ac control is in the off position? Does this indicate another "door" that is not closing correctly? What would this door be called?

Thanks for any help,
Shawn

 

Shawn, whoever worked on your car screwed you... Sure, it's OK for winter, but the seasons will change... The problem you have could be a number of things in that system and without knowing what he did, it'd be hard to tell where to start. If it is a problem with one of the doors, it's not an easy task to gain access to them. As far as the hot air blowing at your feet, it is like that by design, believe it or not. That door remains partially open by design. Getting back to your original problem, it sounds as though the temp cable is "fixed" in that position. Does the rest of your system work as advertised, ie: when you select heat, does the air come out the floor vents, A/C air out the dash vents, defrost air out the defrost vents? If that all works properly, it's a start... I'll try to help you as best I can...

KAM

 

It was the middle of winter and I didn't have time to get it fixed, so I just had him set the temp cable. I've procrastinated until now on fixing it. The controls for the vents work correctly, defrost, floor etc., I think it's the mechanism that closes off the heater core (?). It was described second hand to me as a "door" that was broken and wasn't opening via the temp cable. What about the leg vent - can that be improved? I noticed that on my car ever since I bought it, long before this problem.

 

Check your vacuum lines from the manifold to the controls. Also make sure the vacuum reserve 'ball' (Under the battery tray) is in good condition. Usually one of these pieces goes missing or broken. There should be two vacuum lines running out of the harness, one to the valve and one to the manifold. On the manifold there should be a one-way check valve, then a tee (or combined) going to the reserve ball and to the defroster controls.

 

The guy who looked at it said the door was broken - this was the guy who set the temp cable. He is supposed to be familiar with the cars, although I don't know him. The car was at the radiator shop because they had replaced my heater core last summer, and when it got cold I wasn't getting any heat. The radiator shop checked their work and said it wasn't anything they did, but that this door was broken. They then had this other guy look at it and he set the cable. I asked if it was a vaccum problem then and they said no it was just the door.

 

I think I still have the door in my car--if it's good and you want it you can have it.
Let me know.

 

It definitely sounds like the door and/or cable. I'm not really sure how much you'll have to remove to replace it. All I know about that is that it's up in the dash somewhere. I know that doesn't really tell you much, so maybe the guy who offered you his door can tell you more of what's involved to r&r it...

KAM