AC Compressor and Radiator Fans

AC Compressor And Radiator Fan Diagrams:

AC Compressor And Radiator 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

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

59 Two-pole connector
One adjacent to radiator fan motor 37
One in front of the engine radiator
One at the wiper motor

60 Single-pole connector
At the terminals of the compressor

113 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

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

156 Relay for the 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

170 Compressor for the AC
At the extreme front on the right-hand side, 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

216 Climate control unit
On the facia

23C Distribution terminal +30
In the electrical distribution box behind the glove compartment

Operation
The AC compressor and engine radiator fan are switched on and off from output 23 of climate control unit 216. Cars for certain markets are equipped with auxiliary radiator fan 172 for the AC.

The compressor 170 and auxiliary radiator fan 172 for the AC are switched in by time-delay relay 156. Ordinary radiator fan 37 is switched in by relay 155.

The control coil in time-delay relay 156 will not be energized and the relay will not operate until the following conditions are met:

Contacts H and L in pressure switch 166 must be closed (normal setting). Contacts L will open if the temperature falls to below 0 °C (refrigerant pressure approx. 2 bar), while safety switch H will open if the pressure exceeds 27 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, compressor 170 and auxiliary radiator fan 172 for the AC are switched on.

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

When the engine is running at full speed, pin TK on the relay will be earthed by throttle angle transmitter 203. The relay then switches 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 ignition switch 20 (in the start position). If the "ECON" switch is not depressed at this stage (the green LED is not alight), the AC function will delay relay operation and compressor switching-in by 10 seconds to prevent overloading of the battery.

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 reaches 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.

For fault-tracing hints, also see the section entitled "Air Conditioner (AC)".

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
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).