Abstract: Apparatus and method for controlling a vehicular temperature conditioning system in response to temperature conditioning demand, outdoor ambient air temperature, discharge air temperature, and vehicle engine oil pressure which is indicative of the rotational speed of a clutch and shaft drivingly connecting the temperature conditioning system to the vehicle engine. A cooling mode is initiated if (1) the return air (comfort zone) temperature exceeds a predetermined maximum value, (2) the outside ambient air temperature exceeds a predetermined limit, and (3) the rotational speed of the clutch and drive shaft, as indicated by the vehicle engine oil pressure, is less than a predetermined limit. During operation in the cooling mode, a reheat cycle is initiated in response to the return air temperature and the discharge air temperature.