General Description
All front wheel drive vehicles with transversely mounted engines, use an electric cooling fan. The fan is used for engine coolant and A/C condenser cooling and only operates under certain conditions.
Operation
The electric cooling fan operates when the engine cooling temperature exceeds a certain value. The cooling fan on this engine is totally controlled by the Powertrain Control Module (PCM). The cooling fan has one speed. The PCM turns the cooling fan ON by grounding the coil of the cooling fan relay when certain conditions are met. When the A/C is requested, the cooling fan will also be turned ON.
When the vehicle speed is above 38 MPH, the PCM opens the ground to the cooling fan relay because there should be sufficient air moving through the radiator in order to cool the engine coolant. If the A/C refrigerant pressure or engine coolant temperature becomes excessive or the malfunction indicator lamp (MIL) is illuminated, the PCM may turn the fan ON regardless of vehicle speed.
Cooling Fan Run-On
The Powertrain Control Module (PCM) usually powers down 10 to 30 seconds after the ignition is turned OFF. Since the cooling fan is PCM controlled, the PCM may remain powered up for up to 7 minutes after the ignition is turned OFF to provide a ground in order to energize the cooling fan relay.
This is called a fan run-on and will occur if any of the following combinations of conditions exist when the ignition is turned OFF.
| • | Engine coolant temperature greater than 100°C (212°F) and intake air temperature greater than 80°C (176°F). |
| • | Engine coolant temperature greater than 112°C (234°F) and intake air temperature greater than 70°C (158°F). |
| • | Engine coolant temperature greater than 116°C (241°F). |
The PCM and cooling fan will remain ON until these combinations of conditions no longer exist, up to a maximum of 7 minutes.
If the cooling fan is OFF when the PCM powers down, it will remain OFF regardless of any temperatures until the ignition is turned ON again.
