Air Conditioning Switch: Description and Operation

When A/C is selected (turned ON) inside the vehicle, the A/C switch is ACTIVATED, which sends an input signal to the SBEC. When the SBEC receives this input signal, it engages the compressor clutch by grounding the clutch relay. The engine controller maintains a specific rpm by controlling the Idle Speed Control (ISC) actuator.

If the engine controller receives a signal from the A/C low pressure switch (indicating low Freon level), or the electric clutch cycling switch (indicating evaporator freezing) the A/C relay will be DE-ENERGIZED to de-activate the A/C clutch.