I decided to dive into a problem with my HVAC mode selection problems this weekend. I had air out every duct no matter the mode selected and found two of the blend doors weren't operating properly.

Here is a box I bought from a friend which I intended to use parts from and also as a guide to see how it works. What I found was that the shaft the two visible doors are on had popped out of its hole (actually a slot in the cover piece closed by assembly) on the bottom and neither door operated properly.



Here's what I had to do, just to replace the small cover piece that holds the shafts in place.



Now that I'm almost done buttoning it up (console still needs to go in), I found that the vacuum switch in the controller is acting up. Defrost works fine, HEAT sends air to the vents, VENT sends air to the floor ducts and defrost ducts, haven't checked the A/C functions much. I checked operation of the doors with vacuum and all operate smoothly, but still the modes are messed up - vacuum control switch came from a junkyard some time ago. Is there a difference in vacuum switches from A/C units to non-A/C units?

Here's the piece I replaced. It attaches to the heater box and fit between the box and the ductwork for defrost and dash vents. It's supposed to have a tab on the lower right for a screw to secure it to the box, which keeps the doors' shaft seated in its slot.

 

I worked at cleaning the garage today... I hated it, but I'm sure I had more fun than you did!

 

Yeah, getting behind there wasn't too much fun. I've just got the console to reinstall and have everything working in the HVAC. I found out that the vacuum switch mounts two ways, only one is correct. Now that I have that fixed, I can finish up tomorrow.