Abstract: Methods and devices that use an engine load condition of a vehicle, for example, the vehicle's engine intake manifold or plenum vacuum, to promote the efficiency of the engine. The methods and devices are operable to control the compressor of the vehicle's air-conditioning system, enabling the compressor to be shut off when the vehicle is under relatively high loads. The methods and devices operate by sensing a parameter indicative of an engine load condition of the vehicle, determining a difference between a reading of the parameter and an average based on multiple readings of the parameter, and then engaging and disengaging the compressor clutch depending on whether the reading of the parameter is above or below the average of the parameter. The compressor clutch is engaged if the engine operates under a high load for a duration that is dependent on the average of the parameter.

Abstract: Methods and devices that use an engine load condition of a vehicle, for example, the vehicle's engine intake manifold or plenum vacuum, to promote the efficiency of the engine. The methods and devices are operable to control the compressor of the vehicle's air-conditioning system, enabling the compressor to be shut off when the vehicle is under relatively high loads. The methods and devices operate by sensing a parameter indicative of an engine load condition of the vehicle, determining a difference between a reading of the parameter and an average based on multiple readings of the parameter, and then engaging and disengaging the compressor clutch depending on whether the reading of the parameter is above or below the average of the parameter. The compressor clutch is engaged if the engine operates under a high load for a duration that is dependent on the average of the parameter.