According to one form of the invention, an auxiliary system is provided for supplying air conditioning to the cabin of a truck. The system includes an air conditioning compressor having a jackshaft mounted on a hub of the compressor. The system further includes an electric motor connected to the jackshaft by a belt for the motor, wherein the electric motor has a drive shaft and a pulley rigidly secured thereon, i.e., with no clutch and with no provision for slippage of the pulley relative to the drive shaft. The jackshaft has a pulley thereon for the electric motor drive. An end of the jackshaft that is not proximate to the compressor is rotatably held by a bearing and a bearing bracket in order to increase capability of the jackshaft to withstand side loading.