There was a TSB issued for the defrost door flapper breaking. Well, the other doors aren't exempt from the problem either. The dash only took a couple hours to get out. I could have had it out in a little over an hour but I had to get the steering column out to get to two bolts.

Basically all the HVAC doors are controlled by 12v actuators, operated by +/-12v signals. The actuators are supposed to send feedback to the controller to stop the juice when the door hits the stop point.

Evidently they sometimes want to keep turning and break the teat off the coupler like the one shown here (not broken).

The coupler is a cammed plastic piece the fits inside the door pivot shaft. If the coupler stop breaks, the actuator keeps turning the coupler inside the shaft after the door has completely closed and you end up with this--basically the shaft plastic is stripped out from the cammed coupler shaft turning inside it.


I only purchased one coupler and the foot/face door. I ended up needing all three doors (foot/face door, vent door, and fresh air/recirc door) and two couplers. I don't have another 3 days to wait for parts, so I had to improvise with some superglue and zip ties for the others, but it seems to be working fine. Now the wife can't bitch about not having a defroster! I took my time on the job and I probably spent 8-10 hours of work if you subtract the beer breaks. If I had all the needed parts available and was motivated, I could have had it fixed and buttoned back up in an afternoon. If anybody else has similar problems I suggest buying 3 couplers and the three mentioned doors (the temp control flappers seem to have a solid setup so they should be fine) and replacing them all while the unit is out. Hope this helps. Done.

 

Good info, thanks.

 

can you explain how you knew there was a problem? did only certain vents work or what? very helpful write up by the way/!!

 

I've got an 02 that the temp control doesn't work. I know you said those doors seem solid, but could that be my problem? Seems like a door is loose in there because if I hit the brakes or slow down to fast I get hot air. If I turn it off and accelerate hard or just let it sit for a while it will go back to cold.

 

I only had output from the vents. If I listened closely I could hear the actuators trying to close the vent door when changing to heat or defrost, but got no foot/face air output.

 

I think the 2nd gen might have vacuum controlled HVAC routing. The controls feel like it does. You might be losing vacuum when you use the brakes and that lets the temp control door fall back to hot, but while accelerating or idling it has enough vacuum to keep the door pulled open to bypass the heater core. I would download the factory service manual, read up, and go from there.