Bendix Commercial Vehicle Systems AD-SP SYSTEM PURGE AIR DRYER 10/04 - Manual (Page 28)

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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
® AD-IP ® PuraGuard ® oil coalescing desiccant
cartridge may be contaminated by excess dirt and/or
carbon. Replace the AD-IP PuraGuard oil coalescing
cartridge.
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.
COMPLAINTS COMMON TO THE CHARGING & AIR SUPPLY SYSTEM
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
re-test. If the leakage is OK, repair the compressor
unloader mechanism or replace compressor. If
leakage is NOT OK, then continue inspection.
• Holset ® ECON valve (used with Holset-type “E & QE”
compressor) is missing, malfunctioning, leaking.
• 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 cut-off
valve on system purge air dryers.