General Description
The auxiliary electric
cooling fan consists of (1) radiator support (2) wiring harness (3) bolt/scew
(4) auxiliary cooling fan assembly and provides additonal cooling for low
speed vehicle operations, extended idle, stop and go conditions, and running
the air conditioning system.
Operation
The auxiliary cooling
fan is controlled by the VCM. The VCM controls the ground path for the cooling
fan relay. The relay consists of (1) underhood fuse block (2) auxiliary cooling
fan relay (3) wiring harness and is used to control the high current flow
to run the cooling fan motor. The VCM determines operation of the independent
fans based on various sensor inputs.
The cooling fan is controlled by the VCM based on the following
inputs:
| • | The Engine Coolant Temperature (ECT) sensor |
| • | The Vehicle Speed Sensor (VSS) |
The VCM will turn the auxiliary cooling fan ON when any of the following
conditions exist:
| • | Certain VCM Diagnostic Trouble Codes (DTCs) are set. |
| • | ECT above 107°C (225°F). |
| • | A/C head pressure above 300 psi. |
Once the auxiliary cooling fan has been turned ON by the Engine Coolant
Temperature (ECT) sensor, the VCM will turn the fan OFF when that temperature
has dropped about 4°C (7°F). If the auxiliary cooling fan has been
turned ON by high A/C head pressure, the VCM will turn the fan OFF when the
pressure has dropped to 250 psi. The minimum ON time for the auxiliary cooling
fan is 30 seconds.
