Abstract: An automatic air conditioning system for an automotive vehicle can operate in vent mode, bi-level mode or heater mode, the automatic selection of which is adjusted on the basis of air conditioning-influencing external conditions. The heat value required to adjust the room temperature in a vehicle cabin is derived in accordance with the air conditioning-influencing external conditions. The operation mode is selected depending upon the derived heat value. Changeover between heater, bilevel and vent modes is effected as a function of computed heat value and set-temperature.

Abstract: An automotive air conditioning system has a DEMIST mode which is operative at least in VENT or BI-LEVEL modes for switching conditioned air flow from an upper vent air outlet to a defroster nozzle. In the DEMIST mode, the temperature of air discharged through the defroster nozzle is controlled according to a previously selected, desired temperature so that the air discharged through the defroster nozzle can perform defrosting or demisting of the front windshield as well as conditioning of the temperature in the vehicle cabin. A blower speed control system responds to selection of the DEMIST mode by temporarily adjusting the variation range of the blower speed to not less than a medium speed for a given time period. This helps speed the defrosting or demisting effect of the air conditioning system.

Abstract: The temperature of the air discharged into the upper region of an enclosed space such as an automotive vehicle cabin and the temperature of the air discharged separately into the lower region thereof, is individually controlled in response to a manually inputted command signal (or signals) and in response to at least one (sensed) parameter which affects the environment of said enclosed space whereby the temperature of each region can be varied according to personal taste.

Abstract: An air conditioning unit is directed by a control program which causes it to be sensitive to various internal and external factors affecting the upper and lower cabin environments and is particularly characterized by a blower control which, during initial automatic air conditioner operation, holds the blower energization at a low level(1) in summer so that until cool air is available, hot air is not forcefully discharged into a hot cabin,(2) in winter when both the upper and lower regions are cold and only after a given minimal engine coolant temperature has been sensed to prevent strong drafts of insufficiently heated air, and(3) in winter when the lower region is cold but the upper region is warmed by sunshine, in which case air is blown only into the upper region.

Abstract: The blower of an air conditioner is either (a) rotated at an ultra low speed until a first predetermined air temperature is sensed in the duct in which the blower is disposed, or (b) is temporarily disabled until a minimal engine coolant temperature is sensed, whereafter in both cases the rotational speed of the blower is stepped up a little to a still "low" level and held at this level until the temperature of the air discharged from the duct has risen to a second predetermined temperature. Subsequently the rotational speed of the blower is increased at a suitable rate until a maximum rotational level is reached.

Abstract: The blower of an automotive air conditioning unit is energized according to a flexible schedule wherein the maximum and minimum voltages applied to the blower motor are varied in response to a plurality of sensed parameters which influence the environment controlled by the air conditioning unit so that during extremely hot and cold weather suitably powerful energization is realized while during milder weather the energization is limited to avoid unnecessary noise generation.