COMPLAINTS COMMON TO THE CHARGING & AIR SUPPLY SYSTEM
Complaint: Can Not Build System Pressure
•Discharge line plugged or restricted: see Common
Test 1.
•Air pressure trapped between the governor and compressor unloaders: see Common Test 2.
•Blow leakage at air dryer exhaust: see Common
Test 3.
Complaint: Air System Builds Too Slow
•Discharge line restricted: see Common Test 1.
•Discharge line leakage: see Common Test 5.
•Air leaking at the air dryer exhaust: see Common
Test 3.
•Compressor head gasket failure: apply soap solution around the cylinder head. If leakage between the head and the block is noted, repair or replace the compressor.
•Air pressure is trapped between the governor and compressor unloaders: see Common Test 2.
•Air system leakage: see Common Test 4.
•Bendix®
Complaint: Can Not Build System Pressure Above “X” psi.
•Blow leakage at the compressor unloaders: remove all the hardware from compressor inlet then remove the governor. With 120 psi shop air applied to compressor unloader port, listen for leakage at the inlet. If noted, repair the leak or replace the compressor.
•Incorrect setting on the governor: verify the safety valve operation. Drain the air from the system, remove or disconnect the governor from the compressor and install a gauge in governor unloader (UNL) port. Build system pressure and note when pressure on the dash gauge and test gauge are equal. Both should be equal at maximum setting of the governor.
•Discharge line leakage: see Common Test 5.
•Air system leakage: see Common Test 4.
•Compressor head gasket failure: apply a soap solution around the cylinder head. If leakage is found between the head and the block, repair or replace the compressor.
Complaint: Air Dryer Cycles “ON & OFF” Constantly
This complaint caused by leakage, either service system or supply system. Service system leakage is shown on dash gauges, supply system leakage is not. Note: System purge air dryers will purge more often than those with an integral purge volume.
Service system leakage: see Common Test 4.
Supply system component leakage: drain the system, install a gauge and a shop air hose in place of the drain cock in the supply reservoir. Fill the system to 120 psi, shut off the shop air and check for leakage on the following components in the order presented:
•Compressor unloader leakage.
•Drain the system, remove the governor from compressor and plug the governor UNL port and
•Holset® ECON valve (used with
•Is an ECON valve required, but missing? If YES, install the valve along with special Holset check valve w/choke. If NO, and the ECON valve is present, replace the ECON valve and special check valve. If NO and the ECON valve is not required, then continue inspection.
•Air dryer leakage: Remove the line from air dryer inlet and with 120 psi in the supply reservoir and apply a soap solution to the exhaust and inlet port of air dryer. If the leakage is greater than a one (1) inch bubble in one (1) second at the exhaust port, repair or replace the check valve (on dryers with integral purge volume) or replace the body assembly on system purge air dryers. If the leakage is greater than a one (1) inch bubble in one (1) second at the inlet port, repair or replace the purge valve assembly (on air dryers with integral purge volume) or replace the turbo
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