Cooling fans not turning on

Tiny
CLEETCORTEZ2
  • MEMBER
  • 2009 MERCURY MILAN
  • V6
  • AUTOMATIC
  • 164,000 MILES
When I turn my car on it starts normally, but I’ve realized that the cooling fan doesn’t kick on. I let t idle and it got to about halfway on the meter and the fan still didn’t kick on. What could the problem be?
Saturday, August 10th, 2019 AT 11:04 PM

3 Replies

Tiny
JIS001
  • MECHANIC
  • 3,411 POSTS
Hello and welcome to 2CarPros. Is your vehicle actually overheating or are you concern the fans are not coming on at half way?

I am asking because the gauge is just an "estimate" and does not necessarily mean that is the actual temperature. Please provide more information please.
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Sunday, August 11th, 2019 AT 12:00 AM
Tiny
CLEETCORTEZ2
  • MEMBER
  • 3 POSTS
I don’t know if it’s overheating or not. I try to not let it get past the halfway mark it sat and idled for about 30 minutes and it only got up to half. But I know the fans should at least kick on once the car reaches a certain temperature or I turn the A/C on.
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Sunday, August 11th, 2019 AT 7:59 AM
Tiny
JIS001
  • MECHANIC
  • 3,411 POSTS
The PCM controls the fan speed so if it is not overheating then you should be good. Here is information on how the the fan clutch operates and how it is controlled:

The cooling fan clutch is an electrically actuated viscous clutch that consists of three main elements:

 -  a working chamber

 -  a reservoir chamber

 -  a cooling fan clutch actuator valve and a fan speed sensor (FSS)

The cooling fan clutch actuator valve controls the fluid flow from the reservoir into the working chamber. Once viscous fluid is in the working chamber, shearing of the fluid results in fan rotation. The cooling fan clutch actuator valve is activated with a pulse width modulated (PWM) output signal from the PCM. By opening and closing the fluid port valve, the PCM can control the cooling fan clutch speed. The cooling fan clutch speed is measured by a Hall-effect sensor and is monitored by the PCM during closed loop operation.

The PCM optimizes fan speed based on engine coolant temperature (ECT), engine oil temperature (EOT), transmission fluid temperature (TFT), intake air temperature (IAT), or air conditioning requirements. When an increased demand for fan speed is requested for vehicle cooling, the PCM monitors the fan speed through the Hall-effect sensor. If a fan speed increase is required, the PCM outputs the PWM signal to the fluid port, providing the required fan speed increase.
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Sunday, August 11th, 2019 AT 1:17 PM

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