Well I'm a novice but if the "A/C" button/indicator is lit then the compressor should be engaged. In hot temps it may never cycle. There's a calculator for that which is dependent on ambient temp & humidity. It will even engage in the defrost position as it helps with defrosting by sending dehumidified air to the windshield. Are you saying that even with the fan/system set to "off" the clutch is still engaged?