Hi ,I'm new to the forum. I owned a '91 few years ago and now I just bought another one.






The ac has a strange problem ..




three conditions :

OFF : AC is on and air blows only from floor.

MAX : AC if off !!

NORMAL : AC is on and air blows from upper vents and floor.


(notice) : off and max look like they are switched !!

What could be the problem ?

 

1) blower is always on but is very low speed; this was GM's astro ventilation feature. So the OFF condition is correct.

2) max AC is a special condition of the blower relay. You probably need a new blower relay.

3) this is weird and does indicate the "BiLevel" position is swapped with the Normal.

I'd pull the switch out of the dash and check the vacuum lines. Perhaps the PO has messed with the vacuum line routing somehow. The routing is too complex to list here, but I found section 8A-65-0 in the '88 Service Manual has the complete diagram and color coding for the vacuum lines.