Heater Control Valve: Testing and Inspection

1. Start engine and allow to warm up.
2. Set at 15°C (6O°F) and Auto. (force system to MAX A/C)
3. Feel hose from heater water valve to heater core. Hose should not be hot. This indicates that vacuum is applied to the heater water valve and that the water supply to the heater core is shut off.

In the Econ mode, water should flow to the heater core. If not, check the heater water valve and vacuum supply hose. In case of vacuum leakage or hose collapse, it will not be necessary to replace the entire harness assembly. Replacement can be made by cutting the vacuum hose and inserting a plastic connector. If an entire vacuum hose must be replaced cut hose at the connector, then attach the hose directly to the connector.

Vacuum should be applied to heater water valve and water flow to the heater core should stop when in the Max A/C mode. Repair as required.