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 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 air dryer exhaust: see Common Test 3.
•Compressor head gasket failure: apply soap solution around cylinder head. If leakage between head and block noted repair or replace compressor.
•Air pressure trapped between governor and compressor unloaders: see Common Test 2.
•Air system leakage: see Common Test 4.
Complaint: Can Not Build System Pressure Above "X" psi.
•Blow leakage at compressor unloaders: remove all hardware from compressor inlet then remove governor. With 120 psi shop air applied to compressor unloader port listen for leakage at inlet. If noted, repair leak or replace compressor.
•Incorrect setting on governor: verify safety valve operation. Drain air from system, remove or disconnect governor from compressor and install gauge in governor unloader (UNL) port. Build system pressure and note when pressure on dash gauge and test gauge are equal. Should be equal at maximum setting of governor.
•Discharge line leakage: see Common Test 5.
•Air system leakage: see Common Test 4.
•Compressor head gasket failure: apply soap solution around cylinder head. If leakage between head and block noted repair or replace 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 integral purge volume.
Service system leakage: see Common Test 4.
Supply system component leakage: drain system, install gauge and shop air hose in place of drain cock in supply reservoir. Fill system to 120 psi, shut off shop air and check leakage on following components in order presented:
•Compressor unloader leakage.
•Drain system, remove governor from compressor plug governor UNL port and
•Holset ECON valve (used with Holset Type "E & QE" comp.) missing, malfunctioning, leaking.
•Is ECON valve required but missing? If YES, install, along with special Holset check valve w/choke. If NO and ECON valve present replace ECON valve and special check valve. If NO and ECON not required then next.
•Air dryer leakage: Remove line from air dryer inlet and with 120 psi in supply res. soap exhaust and inlet port of air dryer. If leakage greater than 1” bubble in 1 second at exhaust port, repair or replace check valve (on dryers with integral purge volume) or replace body assy. on system purge air dryers. If leakage greater than 1” bubble in 1 second at inlet port, repair or replace purge valve assy. (on dryers with integral purge volume) or replace turbo
Complaint: System Pressure Goes to 150+ psi
•Drain air system to 0 psi, remove/disconnect governor from compressor. Start engine and note air pressure rise on dash gauges. Apply 120 psi shop air to compressor unloader port. If air pressure continues to rise, repair compressor unloaders or replace compressor. If air ceases to rise, repair or replace governor.
Complaint: Low Pressure Warning After Only 1 or 2 Applications
•Brakes out of adjustment: adjust brakes.
•Excessive system leakage on service (application) side of system: Build system pressure to 120 psi and shut off engine. With park brakes released, make full service application and note dash gauges for 2 minutes. Pressure drop on either gauge should not exceed 4 psi. (2 psi per min.) If pressure drop excessive, find leakage in service system, if OK, then next.
•Incorrect low pressure switch in use or setting incorrect: Build system to 120 psi. Engine OFF ignition ON, slowly drain air pressure from one service reservoir. Low pressure warning on at minimum 60 psi, maximum
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