1997,Chevy, Lumina, 3.1 L
Ok, I have this wird preoblem with my vent system. You know how there are 3 diffrent vents
(floor, the ones on the instrument panel, and the one under the windshield) but lately I
can't switch to the ones on the instrument panel and the other two don't come off. Also my
A/C is very
weak and I think it doesn't work properly. (I am sure that the switches
themself work just fine, I think it's some thing else)


BL:
Sounds like definitely a vacuum problem. The mode switch on the control head controls the
vacuum/electric solenoid block, which in turn, directs vacuum to the proper mode or blend
doors. When there is a loss of main vacuum to the solenoid, the system defaults to def/flor
for safety reasons. First need to check for vacuum at the purple and the black hoses on
the solenoid assembly with the engine running. That is under pass. side dash, above the
blower motor. If no vacuum, check vacuum into the vacuum ball. The engine supplies
vacuum to it. The vacuum ball is under the dr. side inner wheel well shield. One hose
should have vacuum in, the other goes to the solenoid assembly. If vacuum at the
solenoid, possible control head switch problem.

                                                          Back
1- Vacuum/electric solenoid assembly
2- Blower motor
3- Blowe motor resistor
4- Electric actuator
5- Mode vacuum actuator
1- dr. side (left) fender
2- Vacuum ball
Arrow refers to front of car.
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