TM 5-3810-300-24 & P2
Noisy Operation :
Loose drive pulley.
Excessive carbon in cylinder head or discharge line.
Dirty air strainer.
Excessive oil pressure.
Oil return line or passage to engine compressor crankcase flooded.
Oil seal ring in end cover excessively worn.
Piston rings improperly installed.
Compressor Does Not Unload:
Defective unloading piston grommet.
Unloading cavity plugged with carbon.
Unloading mechanism binding or stuck.