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).
EDGE/MKX, FIVE HUNDRED/FREESTYLE/MONTEGO, 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%
Five Hundred/Freestyle/Montego, Fusion/Milan/MKZ:
30% - 90%
Five Hundred/Freestyle/Montego, 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), medium fan control (MFC), and/or high fan control (HFC) outputs. Some applications will have the xFC circuit wired to 2 separate relays.
For 3-speed fans, although the PCM output circuits are called low, medium, and high fan control (FC), cooling fan speed is controlled by a combination of these outputs. Refer to the following table.
If you don't understand these thing's listed above your best bet is to take your vehicle to a qualified repair shop . Have the vehicle checked for DTC'S - diagnostic trouble codes !
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