Patent ID: 8302417

Claim:
A method of operating a vehicle air conditioning system having an engine driven, fixed capacity refrigerant compressor selectively disengageable from an engine by a compressor clutch, the method comprising the steps of: (a) setting a preliminary evaporator air temperature target; (b) charging a cold storage apparatus in the vehicle air conditioning system; (c) determining when the cold storage apparatus has reached a predetermined threshold; (d) when the cold storage apparatus has reached the predetermined threshold, determining a new evaporator air temperature target by: determining a maximum allowable dewpoint evaporator air temperature for maintaining a passenger compartment humidity below a predetermined value; determining a maximum allowable mode evaporator air temperature based on a mode to which the vehicle air conditioning system is set; and setting the new evaporator air temperature target to a lower one of the dewpoint evaporator air temperature and the mode evaporator air temperature; and (e) controlling the compressor clutch to achieve the new evaporator air temperature target.