Elements of the hydraulic drive system of the radiator fan
1 - coolant temperature sensor; 2 - hydraulic pump; 3 - radiator fan control unit (ECU); 4 - throttle position sensor; 5 - ignition unit; 6 - oil filter; 7 - pressure sensor; 8 - hydraulic motor; 9 - oil cooler
Models with V6 engines from 1992 to 1994 have a hydraulically driven radiator fan. The power steering pump on these models has two additional hoses that supply fluid to the power steering mechanism and radiator fan. The fan is controlled by an electronic radiator fan control (ECU) and a solenoid valve that regulates the volume of incoming fluid to the radiator fan.
Examination
Location of the radiator fan control unit, contacts on the electrical connector
1. Connect an additional wire contacts E1 and OP1 electrical connector. In this case, the radiator fan should rotate at a speed of approximately 1100 rpm.
2. The radiator fan control unit is located under the glove box. To test the radiator fan control circuits, remove the lower instrument panel shroud and glove box and disconnect the electrical connector from the ECU.
3. Check the electrical circuits according to the table Checking electrical circuits.
4. To test the coolant temperature sensor, disconnect the electrical connector from the sensor and remove the sensor. Connect an ohmmeter to the sensor contacts, install the sensor in a container with hot water and measure its resistance. The resistance of the sensor at a water temperature of 80°C should be in the range of 1480–1580 Ohm.
5. To check the solenoid valve, disconnect the electrical connector from it and check the resistance of the solenoid valve winding, which should be 7.6-8 ohms at 25°C.
Checking electrical circuits
Control | Tester connections | Condition | Meaning |
Voltage | 1 - Mass | Ignition on | Battery voltage |
Resist. | 2–3 | Solenoid valve cold (25 C) | 7.6 - 8.0 ohms |
Compound | 4 - Weight | Throttle open | Closed |
Compound | 5 - Weight | Throttle closed | Not closed |
Compound | 8 - Weight | A/C pressure connector disconnected | Not closed |
A/C pressure connector connected | Closed | ||
Resist. | 9–10 | Coolant temperature 80 C | 1.48 - 1.58 kOhm |
Replacement
1. To replace the fan or fan motor, drain the coolant and remove the upper radiator hose.
2. Unscrew the connecting bolts and disconnect the pressure hose from the fan motor.
3. Disconnect the return hose. Remove the six screws holding the fan shroud to the heatsink and remove the fan shroud.
4. Secure the shaft of the hydraulic motor of the fan from turning and, turning the fan blades clockwise, unscrew them from the shaft (left hand thread).
5. Remove the three bolts securing the motor to the fan shroud and remove the motor.
6. Installation is made in sequence, return to removal.