1994 Pontiac Grand Prix A/C Mode Stuck

GMC
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LISBELL
  • MEMBER
  • 1 POST
94 grand prix - when a/c is on, max, norm... air will not change from defroster AND floor to dash registers - no matter what the setting is selected. had vacuum checked/repaired by dealer a few months ago because when accelerating the air would decrease-all was well for several months after till the current problem. is the a/c fan direction control vacuum related or is a motor? thanks
Apr 16, 2006 at 2:40 PM
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KENB79764
  • ✓Experienced Mechanic
  • 52 POSTS
the controllers go into a safe mode(defrost and floor heat only) when you have a vacuum leak to a controller under the dash or when one goes bad.
Apr 18, 2006 at 1:50 AM
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Suggested Repair

Check for a vacuum leak to the mode controller under the dash, or replace a failed controller. A leak or bad controller forces the system into default defrost and floor mode.

Conversation Summary

On a 1994 Grand Prix, the A/C airflow stays on defrost and floor and will not switch to the dash vents in any mode. Vacuum was repaired earlier for airflow loss during acceleration. The expert said the controllers enter a safe mode of defrost and floor heat when there is a vacuum leak to a controller under the dash or when a controller fails.

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