RAM 1500 Truck 4WD V8-5.9L VIN Z LDC (1999)
Vacuum Check Valve HVAC: Testing and Inspection
1. Remove the vacuum check valve. One valve is located in the vacuum supply tube (black) at the intake manifold tap on the right side of the engine.
A second check valve is located next to the tee fitting in the vacuum supply tube (black) near the dash panel in the engine compartment. The
vacuum check valve must be removed in order to perform the following tests. See Vacuum Check Valve in the Replacement for the procedures.
2. Connect the test set vacuum supply hose to the heater-A/C control side of the valve. When connected to this side of the check valve, no vacuum
should pass and the test set gauge should return to the 27 kPa (8 in. Hg.) setting. If OK, go to step Step 3. If not OK, replace the faulty valve.
3. Connect the test set vacuum supply hose to the engine vacuum side of the valve. When connected to this side of the check valve, vacuum should
flow through the valve without restriction. If not OK, replace the faulty valve.
