Possible causes, elimination, notes

Diagnosis conditions 

No control module fault stored.

Supply voltage OK.

Nominal blower voltage > 3 volts.

Nominal blower voltage stabilized.

Voltage too low 

1. Check the heating activation relay.

   Battery positive voltage must be present at terminal 87 when the ignition is switched on.

2. Unplug connector C from the heating/air-conditioning control.
3. Connect voltmeter to C 14 (positive) and ground. Switch on ignition.

   Display: Battery voltage

4. Push connector C on the heating/air-conditioning control.
5. Connect voltmeter to C 14 (positive) and C 11 (negative).

   Maximum blower speed

   Display: approx. 12 V

   Minimum blower speed

   Display: approx. 0 V

6. Connect voltmeter to C 14 (positive) and C 16 (negative).

   Maximum blower speed

   Display: approx. 5 V

   Minimum blower speed

   Display: approx. 9 V

7. Check driver.

   Connect voltmeter to positive and pin 3 on driver connector.

   Display: Battery voltage

   Connect voltmeter to positive and pin 1 on driver connector.

   Maximum blower speed

   Display: approx. 5 V

   Minimum blower speed

   Display: approx. 9 V

   Connect voltmeter to positive and pin 2 on the driver connector.

   Maximum blower speed

   Display: approx. 12 V

   Minimum blower speed

   Display: approx. 0 V

8. Check wiring from heating/air-conditioning control to driver for continuity.
9. Check blower motor.

Voltage too high 

1. Unplug connector C from the heating/air-conditioning control.
2. Unplug connector from the driver.
3. Connect ohmmeter to C 16 and ground.

   Display: "INFINITY" ohm

4. Unplug connector from the fan motor.
5. Connect ohmmeter to driver connector pin 2 and ground.

   Display: "INFINITY" ohm