Cooling Fan Description and Operation
Cooling Fan Description and Operation
Cooling Fan Control 2.2L (L61) / 2.4L (LE5)
The engine cooling fan system consists of one cooling fan and two relays. The cooling fan has 2 windings in the motor, one winding is for low speed and the other winding is for high speed. Voltage is supplied to the relays through the 30 A cooling fan 1 and 30 A cooling fan 2 fuses. The engine control module (ECM) controls the low speed fan operation by grounding the cool fan 1 relay control circuit. When the cooling fan 1 relay is energized, voltage is delivered to the cooling fan low speed winding. The ECM controls the high speed fan operation by grounding the cool fan 2 relay control circuit. When the cooling fan 2 relay is energized, voltage is delivered to the cooling fan high speed winding. The cooling fan motor is grounded through its own ground circuit.
The ECM commands Low Speed Fans ON under the following conditions:
* Engine coolant temperature (ECT) exceeds approximately 106�C (223�F).
* A/C refrigerant pressure exceeds 1 310 kPa (190 psi).
* After the vehicle is shut off, the ECT at key-off is greater than 140�C (284�F) and system voltage is more than 12 volts. The fans will stay on for approximately 3 minutes.
The ECM commands High Speed Fans ON under the following conditions:
* ECT reaches 110�C (230�F).
* A/C refrigerant pressure exceeds 1 655 kPa (240 psi).
* When certain DTC's set
When the request for fan activation is withdrawn, the fan may not turn OFF until the ignition switch is moved to the OFF position or the vehicle speed exceeds approximately 10 mph. This is to prevent a fan from cycling ON and OFF excessively at idle.
Resistor Assembly 2.4L (LE5)
The low speed cooling fan supply voltage circuit passes through a single 0.3 ohms cooling fan motor resistor. The resistor assembly is serviceable.
Cooling Fan Control 2.0L (LSJ)
The engine cooling fan system consists of 2 electrical cooling fans and 3 fan relays. The relays are arranged in a series/parallel configuration that allows the powertrain control module (PCM) to operate both fans together at low or high speeds. The cooling fans and fan relays receive battery positive voltage from the underhood junction block. The ground path is provided at G105.
During low speed operation, the PCM supplies the ground path for the low speed fan relay through the low speed cooling fan relay control circuit. This energizes the cooling fan 1 relay coil, closes the relay contacts, and supplies battery positive voltage from the cool fan 1 fuse through the cooling fan motor supply voltage circuit to the left cooling fan. The ground path for the left cooling fan is through the cooling fan s/p relay and the right cooling fan. The result is a series circuit with both fans running at low speed.
During high speed operation the PCM supplies the ground path for the cooling fan 1 relay through the low speed cooling fan relay control circuit. After a 3 second delay, the PCM supplies a ground path for the cooling fan 2 relay and the cooling fan s/p relay through the high speed cooling fan relay control circuit. This energizes the cooling fan s/p relay coil, closes the relay contacts, and provides a ground path for the left cooling fan. At the same time the cooling fan 2 relay coil is energized closing the relay contacts and provides battery positive voltage from the cool fan 2 fuse on the cooling fan motor supply voltage circuit to the right cooling fan. During high speed fan operation, both engine cooling fans have their own ground path. The result is a parallel circuit with both fans running at high speed.
The PCM commands Low Speed Fans ON under the following conditions:
* Engine coolant temperature (ECT) exceeds approximately 106�C (223�F).
* A/C refrigerant pressure exceeds 1 310 kPa (190 psi).
* After the vehicle is shut off, the ECT at key-off is greater than 140�C (284�F) and system voltage is more than 12 volts. The fans will stay on for approximately 3 minutes.
The PCM commands High Speed Fans ON under the following conditions:
* ECT reaches 110�C (230�F).
* A/C refrigerant pressure exceeds 1 655 kPa (240 psi).
* When certain DTC's set
When the request for fan activation is withdrawn, the fan may not turn OFF until the ignition switch is moved to the OFF position or the vehicle speed exceeds approximately 10 mph. This is to prevent a fan from cycling ON and OFF excessively at idle.