Cummins N14 STC, Celect, Celect Plus – Service Manual Air Compressor Will Not Stop Pumping

Air system leaks

Block the vehicle wheels and check the air system for leaks with the service 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 manual. For applications fitted with selective catalytic reduction exhaust systems, check the air supply line to the dosing control unit.

Air governor is malfunctioning or not set correctly

Perform an exhaust gas analysis check. If the exhaust gases are not within specifications, perform the Starting Procedure for New Engine or Changed Conditions. Refer to Procedure 012-017 in Section 12.

Air governor signal line or actuator line is plugged

Inspect the signal line and actuator line. Refer to the OEM service manual.

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.

Unloader valve is malfunctioning

Check the unloader valve and unloader body seal. Refer to Procedure 012-013 in Section 12.

Air compressor inlet restriction upstream

Inspect the air compressor head assembly and replace, if necessary. Refer to Procedure 012-103, Procedure 012-104, or Procedure 012-106 in Section 12.