Air Conditioning (A/C) Compressor Clutch
WARNING: This page is about a different car, the 2015 Ford Fiesta. However, it is still accessible from the selected car via links, so may be relevant.
When battery voltage is applied to the A/C compressor clutch field coil, the clutch plate and hub assembly is drawn toward the A/C clutch pulley. The magnetic force locks the clutch plate and hub assembly and the A/C clutch pulley together as one unit, causing the compressor shaft to rotate with the engine. When battery voltage is removed from the A/C compressor clutch field coil, springs in the clutch plate and hub assembly move the clutch plate away from the A/C clutch pulley.
An A/C clutch diode is integrated into the coil for A/C clutch field coil circuit spike suppression.