A modular and compact air conditioning system is designed to be conveyed by a ground support equipment cart and to occupy minimal space within the cart. The system is constructed within a rectangular frame supporting top, bottom, left side, right side, front side, and back side panels. The top and back side panels contain thin air conditioner condensers. One of the left and right side panels contain an air outlet, and the other contains an air inlet and a duct that may be connected to an airplane to provide cooling air to the airplane. A condenser fan is mounted within the rectangular frame and is arranged to draw outside air in through the condensers and to blow the air out through the air outlet. First and second air conditioners are mounted within the rectangular frame, each including a compressor, an expansion valve, and evaporator coils, with each compressor pumping refrigerant through one of the condensers, through one of the expansion valves, and through one of the evaporator coils and back to the compressor. One of the two evaporator coils is mounted over the air inlet, and the other is mounted over the duct. A variable speed blower is mounted within the rectangular frame adjacent the air inlet, and an enclosed air passage routes air from the air inlet through one of the evaporator coils, the air passage narrowing and routing the air through the blower, the passage then widening and curving around and routing the air through the other of the evaporator coils and through the duct.