Cummins ISX11.9 CM2250 – Service Manual Air Compressor Will Not Stop Pumping

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 in Section 12 and the OEM service manuals. Check for air system leaks in the aftertreatment purge air actuator.
Procedure 011-065 in Section 11.

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 OEM service manual..

Air compressor intake or exhaust system leaks air

Inspect the air compressor head assembly and replace, if required. Refer to
Procedure 012-003 in Section 12
.

Air governor is malfunctioning or not set correctly

Check the air governor for correct operation. Some OEM installations may not utilize an air governor, therefore frequent cycling may be expected and normal. Refer to the OEM service manual.