Engine cooling fan runs constantly even when the motor is cold

2016 FORD F-250
71,000 MILES • 6.7L • V8 • TURBO • 4WD • AUTOMATIC
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RYAN BEASLEY
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It runs all through the RPM range and at highway speeds. It moves if you turn it by hand while the engine is off. The coolant is full and there are no DTC's.
Aug 8, 2019 at 4:10 PM
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ASEMASTER6371
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Good evening,

The PCM controls the fan control. It turns the motor on based on input from the coolant sensor.

Does your temperature gauge work correctly?

Roy
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Aug 8, 2019 at 4:35 PM
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KASEKENNY
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Hi Ryan,

Attached is the description of this fan. It is a viscous coupled fan which means the PCM controls it by pulse width modulating the valve that controls fan speed.

If you said there are no codes, do you have access to live data? Can you look in the PCM and see what the fan is being commanded to do?

If it is being commanded on then you want to then monitor each of the sensors that are listed as inputs to the PCM and see if one of them is reading incorrectly. This would cause the PCM to command the fan on at incorrect times.

If the fan is not being commanded on then more than likely your viscous drive has failed and is stuck open allowing fluid in all the time causing the fan to be locked on.

However, with all this being said, you may want to check with a dealer because this may be covered under Ford's power-train warranty.
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Aug 8, 2019 at 4:45 PM
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