GVL L4-1116cc 1.1L SOHC VIN 2 2-bbl (1988)
Radiator Cooling Fan Temperature Sensor / Switch: Description and Operation
DESCRIPTION
Radiator cooling fan operation is controlled by a radiator mounted thermo switch. Battery voltage is applied to the thermo switch through a fuse in the
fuse panel, and voltage is applied to the cooling fan motor through the thermo switch.
When coolant temperature exceeds 198°F, the thermo switch contacts close, voltage is applied to the fan motor and the fan operates. When coolant
temperature drops below 189°F, the thermo switch contacts open and the cooling fan does not operate.
DIAGNOSIS & TESTING
SYSTEM TEST
1.
Start engine and run until it reaches normal operating temperature.
2.
Monitor coolant temperature using suitable thermometer and observe cooling fan operation.
3.
Cooling fan should begin to operate when coolant temperature reaches 196-200°F, and fan should stop running when coolant temperature drops to
187-191°F.
Fig. 1 Cooling fan & thermo switch installation
4.
If fan fails to operate, stop engine, disconnect electrical connector to thermo switch, Fig. 1, connect suitable jumper between connector terminals,
then turn on ignition switch.
5.
If fan operates, replace thermo switch and recheck system operation.
6.
If fan fails to operate, check for blown fuse, damaged or disconnected wiring or defective fan motor.
COMPONENT TESTING
Fan Motor
1.
Disconnect electrical connector to fan motor, Fig. 1.
2.
Connect battery voltage across terminals using suitable jumper wires.
3.
If fan fails operate, motor is defective.
Thermo Switch
1.
Drain cooling system and remove thermo switch from radiator, Fig. 1.
2.
Connect suitable ohmmeter between switch terminals.
3.
Heat thermo switch in suitable solution while observing ohmmeter.
4.
Meter should indicate continuity when temperature reaches 196-200°F.
5.
Allow switch to cool while observing meter. Meter should indicate no continuity as temperature drops below 187-191°F.
6.
If switch fails to operate as outlined, sensor is defective.
