Fan Control
WARNING: This page does not describe the selected car, but rather 32 other vehicles, including the 2002 Mercury Sable, 2002 Mercury Mountaineer, 2002 Mercury Grand Marquis, 2002 Mercury Cougar, and 2002 Lincoln Town Car. However, it is still accessible from the selected car via links, so may be relevant.
PCM monitors certain parameters such as: engine coolant temperature, vehicle speed, A/C on/off status and A/C pressure to determine engine cooling fan needs. PCM controls fan operation through Fan Control (FC) on single speed fan applications, or Low Fan Control (LFC), Medium Fan Control (MFC) and/or High Fan Control (HFC) outputs on 3 speed fan applications. Although PCM output circuits for 3-speed fans are called low, medium and high fan control, cooling fan speed is controlled by a combination of these outputs. See Fig 1.