A/C works, blows thru defroster and lower but not bi-level on 1997 Oldsmobile Regency

A/C and heater both blow fine upper and lower but neither will blow thru bi-level. Is this a fuse, vacuum hose or what? If it's a hose where would it be and would it be disconnected or something else? Would it be under dash or in engine compartment? Thanks Very Much Bill

by in Crescent, PA on December 28, 2009
1 answer
ANSWER by on December 31, 2009
The a/c mode doors on your 1997 Oldsmobile Regency use engine vacuum to operate. The vacuum source in under the hood. You should find a squarish black plastic tank mounted on the center of the firewall under the hood. Make sure the vacuum hoses are properly connected and you have the proper vacuum supply from the engine. Also check for proper operation of the check valve in the vacuum supply line from the engine.