Air Conditioner Vent Control

[xzz0195]

Vent control on 99 Sierra Quit working on the two settings that blow air outward to passengers. The floorboard and windsheild vents (via controller) appear to work correctly. What's the best way to get started on trouble shooting this?

 

Thanks!

[xzz0195]

I have read here that the first two things to do are to disconnect battery to reset computer, and check the HVAC fuses as well. In fact, some say that disconnecting the HVAC fuses will reset/reprogram the HVAC controllers for the vent doors.

[czycoot1318]

Just went through quite a bit of $$$ to get this figured out. I would check the control panel for the hvac unit. I replaced everything I could then finally gave in and bought a used control panel for $65 from a local junkyard. Fixed my problem which was similar to yours. They said they had a bunch of them as this is a common problem with these trucks.

[xzz0195]

Just went through quite a bit of $$$ to get this figured out. I would check the control panel for the hvac unit. I replaced everything I could then finally gave in and bought a used control panel for $65 from a local junkyard. Fixed my problem which was similar to yours. They said they had a bunch of them as this is a common problem with these trucks.

 

Question on the control panel, is it the whole assembly behind the plastic cover or is it just the single switch? Maybe a better question would be where is the HVAC control panel located? My Haynes manual is silent on vent door issues...