Mirage L4-1597cc 1.6L DOHC Turbo (1989)
Compressor Clutch Relay: Description and Operation
Air Conditioning Relay
When the air conditioner switch is turned on, while the engine is at idle, the Idle Speed Control (ISC) servo operates to increase the engine speed and the
ECU advances the ignition timing, to maintain ideal idle speed. However, there is some delay before the engine speed actually increases. To maintain the
engine free from the air conditioner load during that delay period, the ECU keeps the power off for about 0.5 seconds to open the air conditioner power
relay circuit. As a result, even if the air conditioner switch is on, the air compressor is not driven instantly, preventing engine speed drop due to
compressor load. In addition, for automatic transmission equipped models, during acceleration when the throttle valve opening is above 65°, the air
conditioner power relay circuit is shut off for approximately five seconds to enhance acceleration performance.
