Pump Valve Unit, Checking

Pump Valve Unit, Checking

Special tools, testers and auxiliary items required

• Battery Charger, 60A (VAS 5904)

- Close hood.

- Close doors, windows and sun roof.

- Start engine and let it run for several minutes with maximum cooling performance (compressor is switched on, temperature preselect "LO" for left and right sides).

- Switch off ignition.

- With the ignition switched off, connect the Vehicle Diagnosis, Testing And Information System (VAS 5051 A) to the 16-pin vehicle data link connector with the Diagnostic Cable - 3 Meter (VAS 5051/5A) vehicle diagnosis testing and information system VAS 5051 in the "Guided Fault Finding" function.

- Switch ignition on.

The front A/C control head begins operating, the Coolant Pump (V50) is not activated and does not run and the Left Heat Regulating Valve (N175) and Right Heat Regulating Valve (N176) are activated and closed.

- Read the measured value block. There must not be any deactivations from the Energy Management Control Module (J644) vehicle diagnosis testing and information system VAS 5051 in the "Guided Fault Finding" function.

- Read the measured values for the Left Vent Temperature Sensor (G150) and Right Vent Temperature Sensor (G151) vehicle diagnosis testing and information system VAS 5051 in the "Guided Fault Finding" function.

• Specification: Both measured values indicate the approximate ambient temperature with a maximum deviation of 15 °C.

- Set temperature preselect for left side (driver's side) on front A/C control head to "Hi".

- Read the Left Vent Temperature Sensor (G150) measured value. The temperature value increases.

• Specification: approximately engine temperature operation of Coolant Pump (V50), Left Heat Regulating Valve (N175) open

- Read the Right Vent Temperature Sensor (G151) measured value. The temperature value remains somewhat constant.

• Temperature increase less than 15 °C (Right Heat Regulating Valve (N176) closed)

- Set temperature preselect for right side passenger's side on front A/C control head to "Hi".

- Read the Right Vent Temperature Sensor (G151) measured value. The temperature value increases.

• Specification: approximately engine temperature operation of Coolant Pump (V50), Left Heat Regulating Valve (N175) and Right Heat Regulating Valve (N176) open

- Set temperature preselect for driver's side and passenger's side on front A/C control head to "Lo".

- Read the measure values for the (G150) and (G151).

• Specified Values Temperature drops within 5 minutes to ambient temperature (plus max. 15° C), (operation of Coolant Pump (V50), Left Heat Regulating Valve (N175) and Right Heat Regulating Valve (N176) closed).