Safety Warning
DIY auto repair can cause serious injury, fire, or vehicle damage. These guides are for informational purposes only. Always follow OEM torque specs, wear PPE, and consult a certified mechanic if you are unsure. You are solely responsible for your safety.
Cooling Fan Control
The PCM monitors certain parameters (such as engine coolant temperature, vehicle speed, A/C ON/OFF status, A/C pressure) to determine engine cooling fan needs.
For variable speed electric fan(s):
The PCM controls the fan speed and operation using a duty cycle output on the fan control variable (FCV) circuit. The fan controller (located at or integral to the engine cooling fan assembly) receives the FCV command and operates the cooling fan at the speed requested (by varying the power applied to the fan motor).
The fan controller has the capability to detect certain failure modes within the fan motors. Under certain failure modes, such as a motor that is drawing excessive current, the fan controller shuts OFF the fans. Fan motor concerns may not set a specific DTC. With the fan motor disconnected from the fan controller, voltage may not be present at the fan controller.
EDGE/MKX, FLEX, MKS, MKT, TAURUS, FUSION/MILAN/MKZ, CROWN VICTORIA/GRAND MARQUIS, TOWN CAR: FCV DUTY CYCLE OUTPUT FROM PCM (negative duty cycle)
| FCV Duty Cycle Command (NEGATIVE duty cycle) | Cooling Fan Response/Speed |
|---|---|
| Greater than 0 but less than 5% | Fan OFF, controller inactive |
| Greater than 5% but less than 10% | Fan OFF, controller is in active/ready state |
| Edge/MKX, Crown Victoria/Grand Marquis, Town Car: 10% - 90% | Edge/MKX, Crown Victoria/Grand Marquis, Town Car: Linear speed increase from 30% to 100% |
| Flex, MKS, MKT, Taurus, Fusion/Milan/MKZ: 30% - 90% | Flex, MKS, MKT, Taurus, Fusion/Milan/MKZ: Linear speed increase from 50% to 100% |
| Greater than 90% but less than 95% | 100% |
| Greater than 95% but less than 100% | Fan OFF |
For relay controlled fans:
The PCM controls the fan operation through the fan control (FC), (single speed fan applications), low fan control (LFC) and high fan control (HFC) outputs. Some applications have the xFC circuit wired to 2 separate relays.
For 2-speed fans, although the PCM output circuits are called low and high fan control, cooling fan speed is controlled by a combination of these outputs. Refer to the following tables.
2.0L FOCUS AND TRANSIT CONNECT (with A/C): PCM FC OUTPUT STATE FOR COOLING FAN SPEEDS
| PCM OUTPUT | LOW SPEED | HIGH SPEED | FAN OFF |
|---|---|---|---|
| LFC (FC1) | ON | ON | OFF |
| HFC (FC3) | ON | OFF | OFF |
2.5L ESCAPE AND MUSTANG: PCM FC OUTPUT STATE FOR COOLING FAN SPEEDS
| PCM OUTPUT | LOW SPEED | HIGH SPEED | FAN OFF |
|---|---|---|---|
| LFC (FC1) | ON | ON | OFF |
| HFC (FC3) | OFF | ON | OFF |
NO RELATED
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When to See a Mechanic
Stop DIY work and contact a certified mechanic immediately if any of the following apply:
- • You smell fuel, burning insulation, or see smoke.
- • Brakes feel soft, pull hard to one side, or make grinding noises.
- • The engine overheats, stalls repeatedly, or misfires under load.
- • You are missing required tools, torque specs, or safe lifting equipment.
- • You are not confident in the next step or safety outcome.