Rad cooling Switch on 3.8L 99 Intrigue

[Rolm]

I noticed that my rad cooling fans do not come on,They do come on when I turn on the A/C. I have to assume that the temp sensor switch is defective. Where can I find the switch and how can I test the switch. I have a 99 3.8 Intrigue

[BNaylor]

The engine coolant temperature sensor (ECT) is located right below the thermostat about 3" at the lower intake manifold. Just follow the upper radiator hose to the thermostat housing.

To test ECT use a digital multimeter and check resistance/calibration.

Here are the parameters for cooling fan operation:

There are three basic modes for the fans: OFF, Low-Speed, and High-Speed. These modes are controlled by the Powertrain Control Module (PCM).

Fans OFF:
When the coolant temperature is less than about 220°F (104°C) or
The A/C refrigerant pressure is less than 190 psi (A/C off).

Low-Speed:
When the coolant temperature is between about 220°F (104°C) and 230°F (110°C) or
The A/C refrigerant pressure is more than 190 psi (1310 kPa) or
When car is turned off and the coolant temp is more than about 284°F (140°C) and system voltage is more than 12 Volts. Fans will run for about 3 minutes.

High-Speed:
When the coolant temperature is above about 230°F (110°C) or
The A/C refrigerant pressure is more than 240 psi (1655 kPa) or
When certain DTCs are set.

[Rolm]

Wow what great response and such great detail thank-you I will do what you suggested and update this thread.

[Rolm]

What type of wrench or socket will I need to remove the switch. A regular socket wrench willnot fit over the electrical connector