A/C works. Can turn on and off but cannot change air distribution stays in defrost position. Cannot get max a/c.
Make : GMC
Nothing. Assume swith is electrical?Fuse?
This is most likely caused by a vacuum leak between the AC system under the dash, and the engine. There is a vacuum line and and vacuum reservoir that supply vacuum to operate all of these HVAC functions, and it's typical to find a broken vacuum line under the hood upon inspection.
ASE Master Technician, L1, Master GM Technician. Over 20 years of bumper to bumper GM experience.