coolant air is drawn from the computer cabinet into the expansion device inlet 125 where it is cooled by expansion and delivered to the heat exchanger through expansion device outlet 126 and heat exchanger inlet 127 the pre cooled air is then drawn into the attached heat exchanger air inlet 127 and into an adjacent corrugation channel the pre cooled air is then drawn laterally across the heat exchanger through the lanced perforations 140 in metal fin 132 and exits the heat exchanger assembly through outlet 128 into conduit 120 as is shown in the cut away view of the cpu heat exchanger illustrated in fig6 arrows 142 illustrate the direction of air flow through the heat exchanger assembly to facilitate the installation removal and replacement of processor boards such as board 104 coolant air inlet and outlet tubes 127 and 128 and expansion device 119 are designed to cooperate with corresponding air coupling devices 160 this structure permits connection or disconnection of the board mounted components with the cooling system concurrently with the electrical connection of the board mounted components with the system backpanel 112 an air coupling device 160 is shown in the sectional views of fig7 and 8 the air coupling device comprises a housing 162 which can be plastic piston 164 and metal spring 166 the housing 162 is a cylinder having an opening 168 at one end for receiving air outlet tube 128 a second opening 170 is provided in the wall of.