900 S Sedan L4-2290cc 2.3L DOHC (1994)
When the ICE receives information to the effect that the temperature of the engine has risen to about 100°C it grounds relay 155, causing it to
operate and radiator fan 37 to start.
2-Speed Radiator Fan
Certain cars are equipped with a 2-speed radiator fan to ensure more efficient cooling.
The ICE controls relays 155 and 81.
At an engine temperature of about 100°C
When the ICE receives information to the effect that engine temperature has risen to about 100°C it grounds relay 155, causing the relay to
operate. The voltage supplied to radiator fan 37 is then reduced via resistor 367.
The radiator fan starts and runs at reduced speed.
At an engine temperature of about 113°C
When the ICE receives information to the effect that the temperature of the engine is about 113 °C it grounds relay 81, causing it to operate and
radiator fan 37 to be supplied with current directly.
The second stage of the radiator fan cuts in, i.e. the fan runs at full speed.
Note: All temperatures are those at the thermostat housing.
ICE
The two pressure switches 419 and 166 in the A/C system provide the ICE with information.
If the pressure in the A/C system is too high or if the engine temperature is too high, the ICE switches on the radiator fan at either low or high
speed.
When engine coolant temperature reaches 126°C or more, the A/C system is switched off.
The ICE also sends information to the engine management system telling it that the radiator fans will be switched on or off.
This is done in order to obtain idling speed compensation for the increased or decreased load.
FAULT DIAGNOSIS HINTS
1. Check that fuse 3 is intact and supplied with current.
2. Check that fuse 3 and maxi fuse 1 (2-stage radiator fan) are intact and supplied with current.
3. Check the connectors, wiring harness and ground connections.