Air Conditioning problem
2002 Pontiac Montana 6 cyl Two Wheel Drive Automatic
In short, all controls and vents are working perfectly, EXCEPT the upper rear roof vents. No flow at all, not even residual. Obviously a door is shut somewhere. I found the main blower motor in the rear quarterpanel, and it blows air to the side/floor vents. Is there another motor for the uppers? Or am I looking at a vaccuum hose / actuator door issue?
There should be a door that controls that in the HVAC box where you found the rear blower motor. It may be controlled with an electric actuator instead of a vacuum valve. If you can gain access, remove the actuator and manually work the door to be sure it is ok. Also try with a/c to see if it will flow out of the upper vents, just for laughs.I have seen systems that will only push a/c through top vents for some reason