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Glenn, Senior Master Ford Tech
Category: Ford
Satisfied Customers: 1746
Experience:  26 years exp with Ford Products, ASE Master Auto & Truck + advanced engine perf L1/L2 Gas & Diesel
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Radiator fan will not run when A/C is off car run hot, but ...

Customer Question

Radiator fan will not run when A/C is off car run hot, but it will run with A/C on car still run a little hot but not in the red. It will run fast when unplug the hot and cold senson.
Submitted: 8 years ago.
Category: Ford
Expert:  Glenn replied 8 years ago.
Do the fans run with the a/c on or not?
Customer: replied 8 years ago.
It will run with the A/C on
Expert:  Glenn replied 8 years ago.
From what you said, it sounds like the cooling fans are operating correctly. I would do a feel test on the radiator, if it has cool spots I would suspect that it is clogged up. Is the coolant a nasty brown color?
Glenn and 8 other Ford Specialists are ready to help you
Customer: replied 8 years ago.
I had the radiator clean out
Customer: replied 8 years ago.
Is there another senson that tell the fan to come on when the thermostat open up with the A/C off
Expert:  Glenn replied 8 years ago.

No, it all works off the ECT sensor. How many miles on this van?

I think your head gaskets might be going, have they ever been done before? Pull number 4 spark plug out [left front of eng] and inspect the electrode ground tip for being a shade of green [assuming you have clean coolant in it now]

Customer: replied 8 years ago.
The head gaskets was change when Ford had the recall. I have 196000 miles. When I unplug the ECT sensor the fan run fast. When I plug it back up they STOP and the temperature rise.This is with the A/C OFF. With the A/C ON the fan will run but NOT FAST.
Customer: replied 8 years ago.
I also check the spark plug and it is good
Expert:  Glenn replied 8 years ago.

Ok it is normal for it to run a tad hotter when not running the a/c. Does the fan ever kick in with the a/c OFF?

The fans run all the time due to the a/c requires air flow over condenser, thus the engine runs a little cooler..

With the a/c off, the pcm lets it get a little hotter before engaging hi fan.. This should happen by 3/4 of the way in normal zone of temp gauge. Will really need a computer scan tool to look at the eng temp and when fan is energized to be for sure on this one.

Here is fan strategy from shop manual

The fan control system consists of two two-speed engine cooling fan motors.

The engine cooling fan motors are wired to operate only when the ignition switch is in the RUN position, thereby preventing engine cooling fan motor operation after the ignition switch is turned to the OFF position.

The cooling fan system is controlled during vehicle operation by the constant control relay module (CCRM) and powertrain control module (PCM) (12A650) which will energize the engine cooling fan motors under the following conditions:

  1. Engine cooling fan motors are turned on if:

    1. engine temperature is higher than normal. Engine cooling fan motors start running at 99°C (210°F) and stop running at 96°C (204°F).
    1. A/C is on and vehicle speed does not provide enough natural airflow. Engine cooling fan motors start running at speeds at or below 96 km/h (60 mph) and stop running at 104 km/h (65 mph).
  1. Cooling fan will run at high speed if:

    1. engine temperature is higher than desirable and engine cooling fan motors have been operating at low speed. Engine cooling fan motors start running at high speed at 120°C (225°F) and stop running at 98°C (208°F).

      Windstar vehicles use dual-winding engine cooling fan motors in which low speed fan control is achieved through the dropping resistor.

      The normal operation and cycling of the engine cooling fan motors cause the temperature gauge indicator to read between the mid-point and upper portion of the temperature gauge scale.
      • The slightly higher indicator reading returns to mid-point when radiator electric motor operation begins.
Customer: replied 8 years ago.
You did help but I still have a problem
Expert:  Glenn replied 8 years ago.


did you test the radiator like I suggested, just because you sent it out does not mean its OK. Does coolant ever boil out of the degas bottle?