Grand Cherokee 2WD L6-4.0L VIN S (1997)
Vacuum Check Valve HVAC: Testing and Inspection
Vacuum Check Valve
1. Remove the vacuum check valve. The valve is located in the (black) vacuum supply tube at the engine intake manifold vacuum tap.
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.
