RAM 2500 Van V8-5.9L VIN Z (1997)
Vacuum Check Valve HVAC: Description and Operation
VACUUM CHECK VALVE
A one-way vacuum check valve is installed in the accessory vacuum supply line near the vacuum tap on the right side of the engine intake
manifold. This check valve helps to maintain the system vacuum needed to retain the selected heater-A/C mode settings. It prevents the engine
from bleeding down system vacuum through the intake manifold during extended heavy engine load (low engine vacuum) operation.
The vacuum check valve cannot be repaired and, if faulty or damaged, it must be replaced.