A/C Signal: Description and Operation
PURPOSE/OPERATIONUsed to allow the engine control module to compensate the idle speed for the load of the air conditioner.
When the air conditioner switch is turned on, with engine at idle, the idle speed control motor increases idle speed. However, there is some delay before the engine speed actually increases. To eliminate air conditioner load during that delay period, the engine control module keeps the compressor power off for about 0.5 seconds. As a result, even if the air conditioner switch is on, the air compressor is not driven instantly.
On 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. This improves engine acceleration performance.