A/C Compressor Circuit

WARNING: This page is about a different car, the 2001 Saab 9-3 and 2000 Saab 9-3. However, it is still accessible from the selected car via links, so may be relevant.

A/C request is automatic for ACC system as long as ECON or OFF buttons have not been selected and ambient air temperature is more than 32°F (0°C). A/C request is sent to Dashboard Integrated Central Electronics (DICE) control module. DICE control module will evaluate sensor inputs and when predetermined conditions are satisfied, A/C compressor relay will be energized. A/C compressor runs, even when cooling is not required, to prevent the misting of windshield in damp weather.

Before A/C relay is energized, A/C system pressure in condenser must be 29-392 psi (2.0-27.6 kg/cm² ), evaporator temperature must be more than 39°F (4°C), and engine coolant temperature must be less than 259°F (126°C). When A/C relay is energized, ECM adjusts idle speed based on engine load and speed. When A/C relay is energized, power to A/C compressor clutch is supplied through compressor temperature sensor. During heavy engine loads or high compressor temperatures A/C relay will be de-energized.