Compressor Control System
WARNING: This page is about a different car, the 2001 Subaru Impreza and 2000 Subaru Impreza. However, it is still accessible from the selected car via links, so may be relevant.
With mode control switch in MAX A/C, A/C, defrost/heat or defrost position, A/C system relay activates and sends a signal to Engine Control Module (ECM). This turns on A/C compressor clutch and Fast Idle Control Device (FICD). The main (radiator) fan and sub (condenser) fan also operate. Blower motor relay also operates, determined by fan switch position, to direct airflow.
When thermostat activates, it stops A/C compressor, FICD, main fan and sub (condenser) fan. When dual-pressure switch operates, A/C compressor clutch and FICD stop, but main fan and sub (condenser) fan continue operating. When fan control switch is on, both main fan and sub (condenser) fan operate. See Fig 1.