III. Leakage in the piping the air filter and the main unit's air inlet.

   Common causes of leakage include: improper installation of the air filter; uneven contact area of the air filter; dirt on the contact surface between the air filter and the assembly, causing leakage; the elastic contact pad on the air filter is misaligned; the air filter air filter assembly is cracked, etc.

IV. Excessive moisture on the oil separator filter material causes it to swell and the micropores to contract, the effective separation area of the oil separator, leading to increased resistance and early blockage of the oil separator.