Compressor HVAC: Description and Operation

The compressor has five cylinders and is of axial type up to year model 1987, and has seven cylinders from year model 1988. The pistons are installed annularly around the input shaft.
The valves are of leaf type and are opened and closed by the differences in pressure which arise during piston movement.
The compressor and cylinder head are made of aluminium, while the cylinder bore is made of steel. The pistons are made from aluminium and have a piston ring.
The compressor clutch is electromagnetic.

In M1992, a new vane type compressor was introduced which is specially adapted to R134a refrigerant. In addition, the compressor has overheating protection which switches it off at +140° C.