Mirage L4-1597cc 1.6L DOHC (1990)
Air Conditioning Switch: Description and Operation
Air Conditioning Circuit
When the driver turns on the A/C system, a positive voltage signal is supplied to the ECU (as an indication that the A/C system is needed) and to one
side of the A/C relay coil, located on the left fender apron. The ECU determines if engine conditions are suitable for A/C operation (engine temperature,
idle speed, ignition timing and air/fuel mixture). If the the engine coolant temperature switch is closed (temp. below 235° F) the A/C ON signal is
transmitted to the ECU. If the ECU senses that conditions are suitable for A/C operation, it supplies the ground circuit for the A/C relay coil, energizing
it. This allows the relay to supply voltage to the compressor clutch.
