Owner's manual

17
Bendix
®
AD-RP
™
AIR DRYER TROUBLESHOOTING CHART
SYMPTOMS CAUSE REMEDY
1. Air dryer is constantly
“cycling” or purging.
Air dryer purges
frequently (every
4 minutes or less)
while vehicle is idling.
(continued)
A. Excessive system leakage.
IMPORTANT: Note whether
air pressure loss is shown
on dash gauge(s). Pressure
loss shown on gauges is
caused by service brake
system or component
leakage. Pressure loss NOT
SHOWN on the gauges is
caused by supply system
or component leakage.
(continued)
A. Test ! ttings, hoses, lines and connections. Apply
soap solution to detect excessive leakage. Tighten
or replace, as needed, then repeat the air dryer
charge/purge cycle and observe the gauge installed
in the supply reservoir. If the leakage is within limits,
remove the gauge from the reservoir and replace the
drain cock or valve. If excessive leakage is detected,
continue testing.
Test accessories connected to supply reservoir.
Drain all air pressure from the system, disconnect
all air lines leading to accessories (fan clutch,
wipers, air seats, etc.) and plug the reservoir at the
disconnection point. Build air system pressure until
the air dryer purges and observe the supply reservoir
gauge. If the leakage is no longer excessive, repair or
replace the leaking accessory. If excessive leakage
is detected, continue testing.
Test governor leakage. Build the system pressure to
governor cut-out, turn off the engine and apply a soap
solution to the governor exhaust port and around the
governor cap. Leakage should not exceed a one (1)
inch bubble in ! ve (5) seconds. Reduce the system
pressure to 80 psi or less, and re-apply soap solution.
Leakage should not exceed a one (1) inch bubble in
! ve (5) seconds. If excessive leakage is detected in
either test, repair or replace the governor.
Test compressor unloader leakage. Drain all air
pressure from the system and remove the governor
from the compressor. Temporarily plug the governor
unloader port or the air line that mated with — or
connected to — the compressor. Build the air
system pressure until the air dryer purges, then
IMMEDIATELY SHUT OFF THE ENGINE. Observe
the air gauge in the supply reservoir. If the leakage
is within limits, replace the compressor unloaders.
Re-connect the governor to the compressor (after
removing the plug installed in governor) and retest
while observing the supply reservoir gauge. If
excessive leakage is detected, continue testing.
Test the air dryer purge valve and outlet (delivery)
check valve. Drain all air pressure from the system,
remove the control line connection at the air dryer,
and plug the end of the air line leading to the governor
(not the air dryer control port). Build the system
pressure to governor cut-out and observe the air
gauge. If little or no pressure drop is observed,
replace the air dryer check valve. If the pressure drop
continues, apply a soap solution to the air dryer purge
exhaust and purge control port (where the control
line was removed). Leakage should not exceed a
one (1) inch bubble in ! ve (5) seconds. If leakage is
excessive, repair or replace purge valve assembly.
(continued)