Hi...

The Temp Door on the 91 Z07's HVAC is stuck in the Hot Position (pulled Blower Mod to see etc.), but there are no HVAC Programmer Codes set. The HVAC Programmer reports everything correctly (including the stuck Temp Door's position), and all the other HVAC Functions work fine (like all the Vents and the reported parameters etc). So, it's likely a mechanical problem with the Temp Door.

According to the Manual, this typically requires a new Heater Case, which is discontinued according to my local Chev Dealer. So, if I need one from a wrecker...

a) Are the Heater Cases different between the 84-89 and 90-96 model years?

b) Are the Heater Cases different between the Manual Control and the Electronic Controlled HVAC's (excepting the Temp Door Motor vs Vacuum Actuator etc)?

c) Anyone have any advice regarding R&R'ing the Heater Case?

Thanks...

Doug

 

I dunno if it's the same on yours as my 88, but I had the exact same problem. What you're actually looking for is a plastic clip that costs about $4 from GM. There is a rod connected to that temp door. That rod gets connected to a plastic piece (the one you probably need) that sits on top of a little motor.

I changed mine and it's been working ever since. I had the exact same problems as you.

What I did was. Remove the passenger seat (makes it easier laying on your back to do this). Remove the hush panel (the one with the courtesy light on it. Now, I dropped the ECM to give me more room, was pretty easy to get out. After you get the ECM out, there is a little black box towards the motor of the car. There are 2 screws holding it in that are hard to see. Drop that motor and if the plastic peice is gone or broke, you'll know what the problem is. I plugged my motor back in and changed the temp to make sure the arm on the motor was still working. After you get the little white plastic peice from GM, hook it onto the arm, and then onto the motor and reinstall everything.

Took me probably a total of an hour and a half. I could probably do it now in 30 minutes.

I tried to do a write up of this, but my camera wouldn't take pictures clear enough.

Good luck and if you have any questions I'll help best I can.

 

Thanks...

In looking at the 91's mAnual, they say that you have to pull the Heater Core Case to sevice the Temp Door Motor, which is a huge job etc (dash top, AC Evap Hopusing in Engine Compartment and more).

So on your's, you were able to do the Temp Door Motor Clip without removing the Heater Core Case. I prayt that's the case with the 91 too...(:>)

Thanks again 88vettelover!

Doug

 

I just did this on my 93. Cheap fix, but not fun. You have to pull the inside heater case, time consuming. Door motor sits on top of the case. I dissected the old motor and the main gear had cracked. allowing the motor to just spin without moving the door. I think I spent around $60 for a new door motor from chevy.

 

Thanks HiRiser...

So, I take it I can remove the Top Dash Pad and RH Dash Stuff, then split the Heater Case in the car, and the part that comes off will contain the Motor and Temp Door etc?

I'm in San Mateo BYW...

Thanks...

Doug