Air Conditioning Select Signal

The air conditioning information pertains only to those vehicles with factory installed and aftermarket Jeep air conditioning units. Factory installed air conditioning units are not available for YJ vehicles with 2.5L engines.

When the A/C switch is activated by the driver, and the A/C low pressure switch is closed, a signal is sent to the engine controller. This input signal is referred to as the A/C select signal. If the engine controller receives this input as well as the A/C request input, it will apply the ground to the A/C clutch relay so that the A/C clutch can be ENERGIZED. the engine controller also sends output signals to the Automatic Idle Speed (AIS) motor to raise the idle speed to a predetermined rpm to compensate for the additional load placed upon the engine.

If the A/C low pressure switch opens, indicating low Freon level, the engine controller will not receive the A/C select signal. If the engine controller does not receive the A/C select signal, the engine controller will then remove the ground from the A/C relay, DE-ENERGIZING the A/C compressor clutch.