M11 Series – Service Manual – Air Compressor Will Not Stop Pumping

Symptom Tree  t010

This is symptom tree t010
Cause Correction

Air system leaks

Block the vehicle wheels and check the air system for leaks with spring brakes applied and released. Check for leaks from the air compressor gaskets and the air system hoses, fittings, tanks, and valves. Refer to Procedure 012-019 and the OEM service manuals.


Air governor is malfunctioning or not set correctly

Check the air governor for correct operation. Refer to Procedure 012-017.


Air governor signal line or actuator line is plugged

Inspect the signal line and actuator line. Refer to the manufacturer’s instructions.


Air system component is malfunctioning

Check the operation of check valves, alcohol evaporators, air dryers, and other OEM-installed air system components. Refer to the manufacturer’s instructions.


Unloader valve is malfunctioning

Check the unloader valve and unloader body seal. Refer to Procedure 012-013.


Air compressor intake or exhaust valve leaks air

Inspect the air compressor intake and exhaust valve assemblies. Refer to Procedures 012-103, 012-104, or 012-106.

Last Modified:  05-Jan-2004