1996 Chevrolet Lumina Q&A
1996 Chevrolet Lumina Question: Accessory Vacuum check valve?
On some vehicles, engine vacuum is used to operate the cruise control and heater/AC mode and temperature function. If vacuum is lost these systems will not function correctly. The check valve will is a one way valve that allows vacuum to be supplied and also traps vacuum for the accessory system during times of low engine vacuum - under heavy engine load, when the throttle is open. - Jim Taddei