Solenoid Valve, Shut-Off Valve Heater Box

Solenoid Valve, Shut-off Valve Heater Box












For cars with A/C, the climate control system for certain markets is equipped with a vacuum operated shut-off valve for the heater box. The purpose is to prevent, when needed, coolant from circulating through the heater box so that max cooling is provided. The control module controls a solenoid valve which in turn operates the shut-off valve.

The solenoid valve is supplied from +54 via fuse 21 and is controlled on the ground side by the ACC unit pin 24.

Since the control module grounds the output, the solenoid valve opens and creates a vacuum on the shut-off valve which in turn closes off the coolant flow.

The control module closes the shut-off valve if the requested mixed-air temperature is below 6°C (significant cooling needed).

Diagnosis
In case of an open circuit or short circuit, diagnostic trouble code B2375 is generated, and 18 is shown instead of temperature at calibration.