A transportation refrigeration system is provided including a tractor cabin having an engine and an engine cooling system. A trailer is operably coupled to the tractor cabin. A transport refrigeration unit is configured to maintain a controller temperature environment of a portion of the trailer. The transport refrigeration unit is mounted to a front surface of the trailer adjacent the truck. A shield (50) is mounted to at least one of the tractor cabin, trailer, and transport refrigeration unit. The shield is configured to block an air flow path between an area (42) of discharge air from the engine cooling system and a condenser air inlet (32) of the transport refrigeration unit.