of a second vertical post 48 which is also connected to the pwb 28 together with the first vertical post 42 the second vertical post 48 supports the contactor 18 above the pwb 28 to allow air to flow around the contactor 18 the contactor 18 includes an exterior housing 50 the housing 50 includes a top 52 and sides 54 56 only two sides shown in fig2 in this example the bottom of the housing 50 is provided by a heat exchanger 58 which spans between the sides 54 56 the heat exchanger 58 is rigidly connected to the sides 54 56 in this example and is not configured to move during normal use the heat exchanger 58 may be formed separately from the remainder of the housing 50 and then attached between the sides 54 56 alternatively the heat exchanger 58 may be integrally formed with the housing 50 the heat exchanger 58 includes a base 60 and a plurality of fins 62 projecting outwardly relative to the housing 50 and in this example toward the pwb 28 in fig2 the contactor 18 is closed in particular the input contactor lead 40 is electrically coupled to the output contactor lead 44 by way of the moveable.