Ventilation Fan

Ventilation Fan Diagrams:

Ventilation Fan Components:

Locations of components

7 Earthing point
On the left-hand wheel housing

22A Fuse board
Behind the access panel in the glove compartment

35 Selector switch for the ventilation fan
In the center of the facia

36 Motor for the ventilation fan
In the center of the bulkhead partition

59 Two-pole connector
At the motor for the ventilation fan

74 Resistor for lower speeds of the ventilation fan
In the frame edge of the fan housing, at the cable connection

149 Main switch for the fan
In the heating and ventilation control panel, in the center of the facia

231 Distribution terminal +54
In the electrical distribution box behind the glove compartment


Operation
The supply is taken from fuse 6 to the main switch, fan 149, and then to ventilation fan selector switch 35. The main switch is controlled by the air distribution control, which will open the circuit when it is set to 0.

The fan selector switch controls fan motor 36 across resistor 74 and can be used to set the fan speed to four different values. In position 1, the entire resistor is in circuit, and the fan therefore runs at the lowest speed. In position 4, the supply is shunted across the resistor, and the motor therefore runs at the highest speed.

The earth connection of the fan motor is connected across the terminals of a bi-metal switch in resistor 74 and then to earthing point 7.

1987 model
If the resistor should be overloaded, the heat emitted will actuate the bi-metal switch, so that it will close. The positive supply will be earthed and fuse 6 will therefore blow. When the bi-metal switch has cooled down, it will re-open.

1988 model
On 1988 models, the resistor is also fitted with a fuse.

Fault-tracing hints
The ventilation fan will be operative when the ignition switch is in the drive position.

1. Check fuse 6 and check that the supply to it is live.

2. Check the voltage to selector switch 35 and main switch 149.

NOTE:
Main switch 149 is located in the air distribution control. This switch must be moved from the 0 position to close the supply circuit to selector switch 35.

3. Set selector switch 35 to different positions and check the voltages supplied to motor 36 in each position.

4. Readings across resistor 74:

Speed 1: 3.1 ± 0.3 ohm
Speed 2: 1.15 ± 0.1 ohm
Speed 3: 0.35 ± 0.3 ohm

5. Check the connector, wiring and earth connections.