A/C Clutch Circuit Operation

A 12-volt signal is supplied to the NC request input of the PCM when the A/C is selected through the NC control switch.

The A/C compressor clutch relay is controlled through the PCM. This allows the PCM to modify the idle air control position prior to the NC clutch engagement for better idle quality. If the engine operating conditions are within their specified calibrated acceptable ranges, the PCM will enable the A/C compressor relay. This is done by providing a ground path for the NC relay coil within the PCM. When the NC compressor relay is enabled, battery voltage is supplied to the compressor clutch coil. The PCM will enable the NC compressor clutch whenever the engine is running and the NC has been requested. The PCM will not enable the NC compressor clutch if any of the following conditions are met:
- The throttle is greater than 90%.
- The engine speed is greater than 6315 RPM.
- The ECT is greater than 119°C (246°F).
- The IAT is less than 5°C (41°F).
- The throttle is more than 80% open.