Astra G
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Engine Cooling Module Control Unit The previous procedure for actuating the radiator fans via thermoswitches and plug relays has been modified for the Astra-G. In petrol engines without air conditioning, plug relays remain in use but the thermoswitch is now omitted. The radiator fans are actuated by the engine control unit via plug relays. In the version with two radiator fans (petrol engines with air conditioning and all diesel engines), a new engine cooling module is used. The engine cooling module control unit actuates the radiator fans and switches the compressor. The individual switching stages and speeds of the fan motors are regulated in dependence with the coolant temperature and the air conditioning system pressure. If the input values stipulate that certain switch stages have to be omitted, the system switches to the next lower or higher switch stage at approx. 2 second intervals until the required fan speed is attained. The coolant temperature is supplied by the coolant temperature sensor of the relevant engine management system, and the air conditioning system pressure is determined by a pressure sensor installed in the refrigerant line. The signal from the pressure sensor is also processed by the engine control unit for actuation of the compressor. The compressor is actuated by the engine cooling module control unit. The engine cooling module control unit is located in the front left wheel well for all engine versions. Malfunctions are indicated by a telltale with a new symbol in the instrument panel. Caution: The fan may run on after the ignition is switched "OFF".
2.15.1 Engine Cooling Module Control Unit (continued) • Service Repair work must not be carried out on the engine cooling module control unit. Disconnect the ground cable from the battery before disconnecting the wiring harness plug.
1 Telltale 2 Engine cooling module control unit 3 Engine wiring harness plug 4 Instrument panel wiring harness plug
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