Cummins N14 STC, Celect, Celect Plus – Service Manual Air Compressor Air Pressure Rises Slowly

Symptom Tree  t004

This is symptom tree
Cause Correction

Air intake system restriction to air compressor is excessive

Replace the air compressor air cleaner, if installed. Check the air intake piping. Check the engine air intake restriction if the air compressor air inlet is plumbed to the vehicle or equipment intake system. Refer to Procedure 010-031 in Section 10.


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. 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.


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.


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.


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.

Last Modified:  21-Dec-2011