When it is said that the computer is programmed to engage the fan at different percentages at different coolant temperatures does the percentage refer to the speed of the fan or the time that it is engaged. If my 2005 6 litre fan is not coming on at 220 degrees what should I look for?

 

The percentage refers to fan speed, i.e. 100% means maximum speed. As to what to look for, are you familiar with the melted connector issue? The connector at the fan is prone to overheating and melting. There are many threads on that. I'd start with checking the connector, as well as the fuses.

 

Yes, fan is PWM or duty cycle controlled and expressed as a percent…100% would be on full speed…the chart is below….do you have a DVOM and know how to use it and yes look at the connector…if you start the car with the AC on see if the fan is running…it runs at low speed so you will have to look at it with an inspection mirror.

 

Cooling Fan Control - Variable Speed Single Fan System
The engine cooling fan is a variable speed fan. The engine control module (ECM) controls the fan speed by sending a pulse width modulated signal to the cooling fan control module. The cooling fan control module varies the voltage drop across the cooling fan motor in relation to the pulse width modulated signal.

Cooling fan speed is effected by many different conditions and can be adjusted from 10% to 90% duty cycle (PWM), 90% is considered high speed fan. When multiple cooling fan speed requests are received the ECM uses the highest cooling fan speed of all the requests. The ECM commands the cooling fan ON under the following conditions:

• Cooling fan duty cycle starts when engine coolant temperature reaches approximately 95°C (204°F) and reaches high speed at temperatures above 113°C (235°F).

• Cooling fan duty cycle starts when A/C pressure reaches approximately 1100 kPa (160 psi) and reaches high speed at A/C pressures above 2480 kPa (360 psi).

• At engine oil temperatures above approximately 150°C (302°F) the cooling fan duty cycle will be commanded to high speed.

• At transmission oil temperatures above approximately 132°C (270°F) the cooling fan duty cycle will be commanded to high speed.

• After the vehicle is shut OFF if the engine coolant temperature at key-off is greater than 113°C (235°F) or the A/C pressure is greater than 1720 kPa (249 psi) the cooling fan duty cycle is set to 50%, low speed. If the coolant temperature drops below 110°C (230°F) and the A/C pressure drops below 1660 kPa (241 psi) the fan will shut OFF. The fans will automatically shut OFF after 2 min. regardless of coolant temperature.

 

where is the radiator fan connector located?

 

You will have to get underneath the car.

 

Bottom right of the fan. As said above, you have to get under the car.