Abstract: The air drawn into a diesel engine serially passes through a filter and a cavity, which acts as an acoustic attenuator, before being supplied to the cylinders of the diesel engine. In the cavity the air is in a heat transfer relationship with a heat sink for the electronic components of a microprocessor control. The electronic components may be located in the plenum cavity or in a separate chamber but must have a heat transfer relationship with the cavity, such as through a common wall on which the electronic components are mounted. A heat sink may extend into the cavity.

Abstract: The open grille structure normally directly in front of a condenser coil is replaced with an acoustical barrier which is moved forward of the condenser coil. In moving the acoustical barrier forward, space results at the top, bottom and sides of the unit which can be used to provide inlet openings for inlet air. Acoustical absorption material lines the structure defining the air flow path to the coil. The modified air flow path results in a modified sound path which results in sound attenuation.