Cummins N14 STC, Celect, Celect Plus – Service Manual Air Compressor Cycles Frequently

Symptom Tree  t005

This is symptom tree
Cause Correction

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 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.


E-type system is not plumbed correctly

Install an Econ valve, a check valve, and system hoses. Refer to the Holset® Air Compressors Master Repair Manual, Bulletin 3666121.


Carbon buildup is excessive in the air discharge line, check valve, or cylinder head

Check for carbon buildup. Replace the air compressor discharge line, if necessary. Refer to Procedure 012-003 in Section 12 or Procedure 010-040 and Procedure 010-049 in Section 10.


Air compressor pumping time is excessive

Replace the desiccant cartridge on the Turbo/CR 2000 air dryer. Refer to the OEM service manual. Check the air compressor duty cycle. Install a larger air compressor, if necessary. Refer to the Holset® Air Compressors Master Repair Manual, Bulletin 3666121.


Air dryer outlet check valve is sticking

Lubricate or replace the air dryer outlet check valve assembly. Refer to the OEM service manual.

Last Modified:  22-Dec-2011