Air system leaks
Block the vehicle wheels and check the air system for leaks with service brakes applied and released. Check for leaks from the air compressor gaskets and the air system hoses, fittings, tanks, and valves. For applications fitted with selective catalytic reduction exhaust systems, check the air supply line to the dosing control unit. Refer to Procedure 012-019 in Section 12 and the OEM service manual.
Air governor is malfunctioning or not set correctly
Check the air governor for correct operation. Make sure the air governor is located less than 0.6 m [2ft] from the air compressor. Refer to Procedure 012-016 in Section 12 and 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 manufacturer’s instructions.
E-type system is not plumbed correctly
Install an Econ valve, a check valve, and system hoses. Refer to the OEM service manual.
Air compressor intake or exhaust valve system leaks air
Leak Test the air compressor head assembly intake and exhaust valve. Refer to Procedure 012-014 in Section 12. The intake and exhaust valve on the air compressor head are not serviceable, replace the air compressor cylinder head. Refer to Procedure 012-007 in Section 12.
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 OEM service manual.
Air dryer outlet check valve is sticking
Lubricate or replace the air dryer outlet check valve assembly. Refer to the manufacturer’s instructions.