Bravada 2WD L6-4.2L VIN S (2002)
Heater Control Valve: Description and Operation
HVAC Systems - Automatic
COOLANT BYPASS VALVE
The coolant bypass valve controls coolant flow to the auxiliary heater core. Integral to the coolant bypass valve is an electric solenoid that controls
vacuum flow to open and close the valve. When the HVAC control module applies 12 volts to the integral solenoid, the solenoid applies vacuum to a
diaphragm that closes the water valve. This action restricts coolant flow to the auxiliary heater core. The coolant bypass valve is a normally open
valve. If there is a concern with control of the valve or with its vacuum source the valve will still be able to supply heated coolant to the auxiliary
heater core.
