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Individual Servo Tests

Check the individual servos for correct operation and freedom from leaks.

Vacuum Pump Connection:





Warning: Disconnect the plug (1) at the vacuum pump to prevent vacuum from being built up uncontrollably.

Before test can be carried out, the ignition must be switched off.

Control Panel:





- Set the airflow selector wheel as shown in image.
- Set the temperature selector wheel to cold (16°C/61°F).
- Vacuum must have stabilized at approximately 400 mbar (11.75 in Hg).
- All push buttons must be off.
- All vent slots must be open.

Switch ignition "ON".
- The water valve will close (vacuum is applied).
- The defroster flap will close (vacuum is applied).
- Open the vent flaps (both stages, vacuum applied).
- Blower motor voltage 4.5V.

Air Flow Diagram:





- For air outlets, see image.
- The vacuum will drop for a short period, then stabilize.
- If the vacuum does not drop, the above-mentioned servos have failed to operate.

Trouble-shooting:
- No actuating signal supplied to solenoid valves - defective solenoid valves or servo.
- If vacuum drops steadily - leaks in vacuum operating circuits.

Air Flow Diagram:





Press the TOP/BOTTOM push button.
- The footwell flap will open (vacuum applied).
- The stage 1 defroster flap will open (without vacuum application).
- The stage 1 and 2 vent flap will close (without vacuum application). For air outlets, see image.
- Vacuum will drop for a short period, then stabilize.
- If vacuum does not drop, the above-mentioned servos have failed to operate.


Trouble-shooting:
- Actuating signal to solenoid valves, the solenoid valves themselves or the servos.
- If vacuum drops steadily - leaks in the above-mentioned operating circuits.

Air Flow Diagram:





Turn the temperature selector wheel to maximum heat (32°C/90°F).
- Allow a period of approximately 1/2 minute for the switching action to take effect.
- The water valve will open (no vacuum applied).
- The stage 2 defroster flap will open (no vacuum applied).
- The footwell outlet is open (vacuum is applied).
- The airflow increases compared with the preceding test stage.
- There is no vacuum drop.


Air Flow Diagram:





Press the "Max. open" push button for the air conditioning.
- The vent flap will open (vacuum applied to both stages).
- The footwell outlet will open (vacuum applied).
- For air outlets, see image.
- Vacuum will drop for a short period, then stabilize.
- If vacuum fails to drop, the above-mentioned servos have not operated.

Trouble-shooting:
- Defective signal supply to solenoid valves, the solenoid valves themselves or the servos.
- If vacuum drops steadily - leaks in the above-mentioned operating circuits.

Preconditions for the next test stages:
- Airflow selector wheel in position ( [] [] [] )
- Temperature selector wheel to cold (16°C/61°F).
- Vacuum stabilized at approximately 400 mbar (11.75 in Hg).
- All push buttons switched off.
- All vent slots opened.
- Ignition switched "ON".

Air Flow Diagram:





Press the button for the rear seat area.
- The rear seat area flap will open (vacuum is applied).
- Vacuum will drop for a short period, then stabilize.
- For air outlets, see image.
- If vacuum does not drop, the servo stated above has failed to operate.

Trouble-shooting:
- Solenoid valve actuating signal, solenoid valve or servo.
- If vacuum drops steadily - leaks in the above-mentioned operating circuit.

Air Flow Diagram:





Press the RECIRCULATING AIR button.
- The fresh air flaps will close (vacuum applied) and the recirculating air flaps open (vacuum applied).
- Air outlets: as for preceding test stage.
- No air is drawn in through the fresh air grille.
- Vacuum drops for a short period, then stabilizes. If vacuum does not drop, the above-mentioned servos have failed to operate.
- (Defective solenoid valve operating signal, solenoid valves or servos.)
- If vacuum drops steadily, there are leaks in the above-mentioned operating circuits.


Air Flow Diagram:





Switch off RECIRCULATING AIR and rear seat area outlet again.
- Set the temperature selector wheel to cold (16°C/61°F).
- Turn the airflow selector wheel from ( [] [] [] ) to ( [] [] ).
- The left fresh air flap will close (vacuum applied).
- The airflow will be reduced.
- Vacuum will drop for a short period, then stabilize.
- If vacuum fails to drop, the servo stated above has not operated. Check actuating signal to solenoid valve, the solenoid valve itself or the servo to locate the failure.
- If vacuum drops steadily, there are leaks in the above-mentioned operating circuit.

Air Flow Diagram:





Turn the airflow volume selector wheel from ( [] [] ) to ( [] ).
- The right stage 1 fresh air flap will close (vacuum applied).
- The airflow will be reduced.
- Vacuum will drop for a short period, then stabilize again.
- If vacuum fails to drop, the servo stated above has not operated.


Trouble-shooting:
- Solenoid valve actuating signal, solenoid valve or servo failed.
- If vacuum drops steadily, there must be leaks in the above-mentioned operating circuit.


Air Flow Diagram:





Turn the airflow volume selector wheel from ( [] ) to 0.
- The left stage 1 fresh air flap will close (vacuum applied).
- No further air will emerge.
- Vacuum will drop for a short period and then stabilize.
- If the vacuum does not drop, the servo stated above has failed to operate.


Trouble-shooting:
- Solenoid valve actuating signal, solenoid valve or servo failed.
- If vacuum drops steadily, there must be leaks in the above-mentioned operating circuit.
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