In one or more implementations, an example air heater assembly is described. The air heater assembly includes a frame defining an aperture and an air heater that includes at least one heating element. The frame is configured to receive the air heater. The air heater assembly includes a terminal configured to connect with the at least one heating element. The air heater assembly includes a hard coated bushing configured to receive the terminal, and the hard coated bushing is configured to be received within the aperture to form a seal and to electrically isolate the terminal from the frame.