Posts Tagged: heater control valve

Diagnose a heater control valve

No heat due to bad heater control valve In some cars, the heat is regulated by a heater control valve that controls the flow of hot engine coolant from the engine to the car’s heater core. On older vehicles, the valve is operated by a cable, while newer vehicles used a vacuum actuator controlled valve. A heater control valve can fail in several ways. Since a vacuum operated valve defaults to the fully open heat-on position when vacuum isn’t applied, a loss of vacuum is the first thing to suspect … Read More