The Air Supply Unit (ASU) is located on the vehicle frame rail on the passenger side of the vehicle. The ASU contains the air dryer, compressor, exhaust valve, valve block, pressure sensor, and temperature sensor.
The compressor itself is suspended from the ASU mounting bracket by three spring loaded studs to reduce vibration and noise. The valve block is bolted to a mounting bracket that is in turn bolted directly to the side of the ASU mounting bracket. The ASU is serviced as an assembly.
The compressor cannot refill the reservoir and the complete system if all pressure is exhausted, as in a compressor assembly or valve block replacement. The system will need to be filled at the reservoir with nitrogen. For complete filling of the air suspension system after a repair (Refer to 17 - Rear Suspension/Standard Procedure) .