9-3 Coupe (9400) L4-2.0L Turbo (B205) (2001)
Compressor HVAC: Description and Operation
Compressor (petroleum)
The A/C compressor on the Saab 9-3 (petroleum) is mounted on the right front side of the engine and its function is to increase the pressure of the
refrigerant that is required for the correct operation of the A/C system.
A lot of power is required to achieve this pressure increase. The compressor takes this power from the crankshaft via a belt system which also drives the
generator and power steering pump.
Cut-in and cut-out is accomplished through an electromagnetically controlled mechanical clutch that is integrated with the compressor belt pulley. There
is an overheating protection on the compressor that will cut-out if the temperature exceeds +120°C. The compressor will cut- in again when the
temperature has dropped below +105°C. Corresponding actual temperature of the compressor is then 140-150°C at cut-out and 115-125°C when it cuts
in.
If the compressor is overheated, for example, if the amount of refrigerant in the A/C system is insufficient or if the expansion valve is clogged, it will
cycle (cut-in and out repeatedly) until the temperature decreases.
The compressor is equipped with a non-return valve located in the outlet on the high-pressure side. The non-return valve prevents refrigerant from
flowing back to low-pressure side during the normal operation of the compressor but also when it has stopped.