Grand Cherokee 4WD L6-242 40L VIN S MFI (1993) - Vacuum Check Valve HVAC TSB | Page 6121
Vacuum Check Valve HVAC: Testing and Inspection
1. In the engine compartment, disconnect the Heater-A/C vacuum supply (black) hose. This hose passes through an opening in the dash panel.
2. Remove the vacuum check valve. This valve is located on the (black) vacuum supply hose at the intake manifold.
3. Connect test vacuum supply hose to the HEATER SIDE of the valve. In this direction the gauge should return to calibrated setting. If valve leaks
vacuum in this direction, valve replacement is necessary.
4. Connect test vacuum supply hose to the ENGINE VACUUM SIDE of the valve. Vacuum should flow through valve.
