Car A/C Compressor Magnetic Clutch

By 3 August 2014

The compressor is driven by the engine crankshaft via a pulley system. In Figure 2.21 the pulley system provides permanent drive to the multi groove drive belt (4). This means once the engine is started the multi groove drive belt pulley is rotating.There is an air gap between the multi groove drive belt pulley and the drive plate (1).When the engine is running the compressor is stationary until the A/C button is selected and electrical power flows through the clutch field coil generating an electrical magnetic field which attracts the drive plate towards the multi groove drive belt pulley (Fig. 2.20). The drive plate which is attached to the compressor drive shaft is pulled towards and held against the multi groove drive belt pulley system. The clutch is now held together as one unit and the compressor’s rotational speed matches the engine speed.When the A/C system is either being cycled or is no longer required the current is switched off and the magnetic force created in the clutch field coil depletes (Fig. 2.21). The drive plate disengages through the help of return springs and the compressor stops.