02Bendix Charging Treatment and Storage Systems Troubleshoot

Complaint: Air Dryer Cycles “ON & OFF” Constantly This complaint is caused by leakage - either service system or supply system. Service system leakage is shown on dash gauges. Supply (wet tank) system leakage is not. Note: System purge air dryers may purge more often than those with an integral purge volume. Air system leakage (See Common Test 1) 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 • • Drain the system, remove the governor from the compressor, plug the governor UNL port and re-test. If the leakage is OK, repair compressor unloader mechanism or replace compressor. If the leakage is NOT OK, then continue. (See Common Test 4) Holset ECON valve (used with Holset Type “E & QE” compressors) • • Check for missing, malfunctioning or leaking ECON valve. If a Bendix DI (Drop-In) with a soft seat purge valve air dryer is installed, the ECON valve is not required. • • Is ECON valve required, but missing? If YES, install it and a special Holset check valve with choke. If NO, and ECON valve is present, replace the ECON valve and special check valve. If NO, and an ECON valve is not required, then continue. Air dryer • • Check for leakage. • • Remove the line from the air dryer inlet and - with 120 psi in the supply reservoir - soap the exhaust and inlet port of the air dryer. If the leakage is greater than 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 compressor is a Holset type E or QE, verify the air dryer in use contains a soft seat purge valve. If the leakage is greater than one (1) inch bubble in one (1) second at the inlet port, repair or replace the purge valve assembly (on dryers with integral purge volume) or replace the turbo cut-off valve on system purge air dryers. Complaint: System Pressure Goes to 150+ psi • • Drain the air system to 0 psi; remove and disconnect the governor from the compressor. Start the engine and note the air pressure rise on dash gauges. Apply 120 psi shop air to compressor unloader port. If air pressure continues to rise, repair the compressor unloaders or replace the compressor. If the air pressure ceases to rise, repair or replace the governor. Complaint: Low Pressure Warning After Only 1 or 2 Brake Applications Brakes out of adjustment • • Adjust the brakes. • • Ensure proper operation of the tractor protection valve. Excessive system leakage on service (application) side of system • • Build the system pressure to governor cut-out and shut off the engine. With the park brakes released, make a full service application and note the dash gauges for two (2) minutes. The pressure drop on either gauge should not exceed 4 psi. (2 psi per min.) If the pressure drop is excessive, find the leakage in the service system. If it’s OK, then continue. Incorrect low pressure switch in use or setting incorrect • • Build the system pressure to governor cut-out. With the engine OFF and ignition ON, slowly drain the air pressure from one service reservoir. The low pressure warning will come on at minimum 60 psi, the recommended maximum is 10-15 psi less than the governor cut-in pressure.