Ok, since I got my 89 coupe two years ago, the heater and air have never worked.

I usually only drive it when it's warm out, and I usually have the windows down, so it's no big deal. But, I finally got most of my other problems worked out, and want to try to get this fixed as well.

From what I've read, this is probably the heater temp door (which I've heard called by a bunch of different names here.)

I've taken off the blower module, and looked inside both when the temp is set to 90, and when it's set to 60, and everything looks the same. So, either the door is not moving, or I'm looking at the wrong thing. Has anyone tried to snap a picture of what it looks like in there? I'm not sure it would work, but it would sure be helpful!

So, if it is indeed a bad motor, or a broken clip, I've read that you need to tear things down almost to the degree of replacing the heater core. If i'm going that far, I suppose I should just replace the core as well. Or, I may be doing the same procedure in the future. What do you think?

Can anyone provide advice?

Thanks!

--- John

 

I don't have the service manual way/flowchart to troubleshoot the system, but from what I remember, you should check for any codes in the dash control. It can only be 3 or 4 things, so I didn't really loose much checking them in no particular order.
So, you removed the BCM

I understand the system goes thru a check cycle on start up or after the battery gets disconnected and then reconnected(????)
-or-
you could have the engine running(to provide the necessary vacuum to the HVAC system) and have someone inside the car press the up temp button(start it at 60*). You should see

the door moving from left to right.
If it doesn't, could be no vacuum is in the system, or as you mentioned, the clip is not functioning as it should with the rod.

The clip circled in yellow is one of two. The other one is in an excellent picture fellow member brookman took. Check it out here:
http://forums.corvetteforum.com/show...highlight=door
Another place to check is the solder on the resistors of the circuit board that controls the system. This CB is housed inside a small black plastic box mounted vertically to the interior firewall next to the steering column, behind the brake pedal. Here's a pic

You could re-solder the joints, or replace the resistors all-together(with new solder).
Check the tubing that supplies the system with vacuum also. I'm sure it's brittle now.
It starts at the back of the intake plenum(engine) and goes into a check valve, a "T" and an elbow. Those items are missing in my pic (line is over my left thumb)



If that line has a break in it, the vacuum leaks out and the system has no oomph. Might have to replace this line with new tubing or hose.

 

Whoa! Thanks for the very complete description!!!

It looks like I was looking at the wrong thing, and will re-check it today!

Thanks for the help! and especially the pictures!