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 systerm.
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) under hood fuse relay center (2) auxiliary cooling fan relay
(3) wiring harness and is used to control the high current flow to power the
cooling fan motor. The VCM determines operation of the independent fans based
on various sensor inputs.
Auxiliary Cooling Fan
The auxiliary 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 at idle:
| • | Certain VCM Diagnostic Trouble Codes (DTCs) are set. |
| • | ECT above 107°C (225°F). |
| • | A/C head pressure above 225 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 180 psi. The minimum ON time for the auxiliary cooling
fan is 50 seconds.
