Air Conditioner (AC)

Air Conditioner (AC) Diagrams:

Air Conditioner (AC) Components:

Locations of components

3 Earthing point, facia
At the left-hand front speaker socket

7 Earthing point
On the left-hand wheel housing

16 Instrument lighting rheostat
On the left-hand side of the facia

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

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

37 Radiator fan
On the left-hand side of the engine radiator assembly

38 Recirculation damper motor (recirculation valve)
In the engine compartment, at the top in the right-hand corner

59 Two-pole connector
One adjacent to radiator fan motor 37
One at the front, at the engine radiator
One at the wiper motor
One adjacent to recirculation damper motor 38

60 Single-pole connector
At the terminal of the compressor

74 Resistor for radiator fan
At the frame edge of the fan housing, at the cable connection

113 Time-delay relay for the rear window heater
In the electrical distribution box behind the glove compartment

123 Four-pole connector (1987)
On the accumulator/dryer unit, below the windscreen on the right-hand side

143 Recirculation switch for the AC
In the facia, between the centre console and the steering wheel

149 Main switch for the fan
In the centre of the facia

155 Relay for the AC radiator fan
In the electrical distribution box behind the glove compartment

156 Relay for the AC and ACC radiator fan
In the electrical distribution box, behind the glove compartment

158 Negative distribution terminal
In the electrical distribution box behind the glove compartment

159 Distribution terminal +15
In the electrical distribution box behind the glove compartment

166 Pressure switch for the radiator fan
On the accumulator/dryer unit, below the windscreen on the right-hand side

169 Switch for the AC
On the facia, between the centre console and the steering wheel

170 Compressor for the AC
On the right-hand side at the front, above the manifold

171 Anti-freeze thermostat (cycling clutch switch)
On the evaporator housing, below the windscreen on the right-hand side

172 Radiator fan for the AC
Behind the grille on the right-hand side, in front of the condenser

173 Diode for the AC compressor
At the AC compressor (in the wiring)

200 Control unit for the LH fuel system
On the left-hand side of the bulkhead

201 Engine earthing point
At the engine lifting lug

203 Throttle angle transmitter
On the intake manifold

230 Distribution terminal +30
In the electrical distribution box behind the glove compartment

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

Operation
Some cars are equipped with an Air Conditioner (AC).

The AC can be switched on and off by means of AC switch 169. Compressor 170 and auxiliary radiator fan 172 for the AC are switched in by relay 156. Ordinary radiator fan 37 is switched in by relay 155.

Compressor and AC radiator fan
The following conditions must be satisfied before switch 169 is energized from fuse 6:

Ventilation fan main switch 149 must be closed, i.e. the air distribution control must be open.

The ventilation fan must be switched on, i.e., switch 35 must be in one of the positions 1 - 4.

When switch 169 is depressed, its built-in lamp will be supplied directly. The lamp will then light up at full intensity. (If the switch is not operated, the lamp will be supplied across rheostat 16.)

The following conditions must also be satisfied before the operating coil and contacts in time-delay relay 156 are energized and the relay operates:

Contacts H and L in pressure switch 166 must be closed (normal setting). Safety switch H will open if the pressure should exceed 27 bar, while contacts L will open if the temperature should fall below 0 °C (refrigerant pressure: approx. 2 bar).

The contacts of anti-freeze thermostat 171 must be closed, i.e. the ambient temperature must be at least approx. +6 °C.

When the relay coil is energized, the relay will operate and compressor 170 and auxiliary radiator fan 172 for the AC will be switched on.

Compressor operation is delayed to ensure that the engine speed will not fall when the unit is switched on with the engine idling. The delay allows the fuel injection controller to raise the idling speed as required.

When the engine is running at full throttle, pin TK on the relay will be earthed by throttle angle transmitter 203. The relay will then switch off the compressor in order to relieve the engine of the compressor load and thus enable it to develop maximum power.

The relay is provided with a further time-delay function which is activated each time the engine is started, i.e. when pin 50 is supplied from the ignition switch (in the start position). If switch 169 is depressed at this stage, relay operation and compressor switching-in will be delayed by 10 seconds to prevent overloading of the battery.

LH 2.2 fuel injection system
Control unit 200 for the fuel injection system receives information via pin 16 of relay 156 as to whether the relay time-delay function has been activated, so that idling compensation can be initiated. Operation of the relay is followed by switching-in of the compressor 0.6 seconds later. The relay contacts are supplied across pin 15 (when the ignition switch is in the drive position).

LH 2.4 fuel Injection system (1988-I16 Lambda)
Control unit 200 for the fuel injection system receives information via pin 87B of relay 156 as to whether the relay time-delay function has been activated, so that idling compensation can be initiated. The relay contacts are supplied across pin 15 (when the ignition switch is in the drive position).

Radiator fan 37
Ordinary radiator fan 37 is operated by contacts M in pressure switch 166. The contacts are normally open when the unit is started. When the refrigerant pressure has reached 15 bar, the contacts will close and relay 155 will be energized. Fan motor 37 will then be supplied across fuse 23 and will start.

The contacts open and close in response to the amount of cooling necessary. The contacts open at 11 bar.

Recirculation
In the recirculation setting, the air flow path is reset by means of a recirculation damper operated by switch 143.

In the normal setting, terminal 2 of the switch supplies a positive voltage across cable 404 GN to recirculation damper motor 38. From terminal 7 the other terminal of the motor is earthed across cable 405 BL. The damper to the interior is closed and the air is drawn from the outside.

When recirculation is selected by depressing switch 143, this switch will reverse the polarity on the two cables. The motor is reversed and the recirculation damper opens.

When the switch is depressed, its built-in lamp will be energized directly, and the lamp will light up at full intensity.

Fault-tracing hints
A general hint is that the AC system is connected to the supply when the ignition switch is in the drive position. If malfunction has occurred and no faulty component can be found, check the wiring, connectors and earth connections.

AC compressor and AC radiator fan

1. Check fuses 20 and 6 and check that the supply to the AC switch and relay 156 is live.

2. Depress the AC switch. Check that the supply to pressure switch 166 is live. Check that the pressure switch closes when its operating conditions are satisfied. NOTE: Refrigerant will spray out if the pressure switch is disconnected for checking. CAUTION: Risk of frostbite.

3. Check anti-freeze thermostat 171. (The temperature must be at least about +6 °C for the contacts to close the circuit.)

4. Check that the relay coil is energized and that the supply to relay contacts 87 and 87A is live. If not, check that the coil and contacts are supplied from thermostat 171 and from terminal +15.

When the relay is energized, pin 16 should be live. When the throttle valve is fully open, pin TK should be earthed.

Ordinary radiator fan

1. Check fuse 23 and check that the supply to the contacts of relay 155 is live.
2. Depress the AC switch and check pressure switch 166 as described above.
3. Check that the relay coil is energized from pressure switch 166.
4. Check that voltage is supplied from pin 87 of the relay contacts.

Recirculation

1. Check fuse 4 and check that the supply to it is live.
2. Check that terminal 2 of switch 143 is live when the switch has not been depressed (no recirculation).
3. Check that terminal 7 of switch 143 is live when the switch has been depressed (recirculation).