Bendix Commercial Vehicle Systems AD-9 AND AD-9 IPC AIR DRYERS 4/11 - Manual (Page 20)

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Bendix ® AD-9 ® AND AD-9 ® IPC AIR DRYER TROUBLESHOOTING CHART
SYMPTOMS CAUSE REMEDY
1. Dryer is constantly “cycling”
or purging. 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 gauges is caused by supply
system or component leakage.
(continued)
1. Test fi 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 leakage is within limits,
remove gauge from reservoir and replace drain cock or valve. If
excessive leakage is detected, continue testing.
2. Test accessories connected to supply reservoir. Drain all
air pressure from system, disconnect all air lines leading to
accessories (fan clutch, wipers, air seats, etc.) and plug the
reservoir at disconnection point. Build air system pressure until
air dryer purges and observe supply reservoir gauge. If leakage
is no longer excessive, repair or replace leaking accessory. If
excessive leakage is detected, continue testing.
3. Test governor leakage. Build system pressure to governor cut-
out, turn off engine and apply soap solution to governor exhaust
port and around cap. Leakage should not exceed a 1 in. bubble
in 5 seconds. Reduce system pressure to 80 psi or less, and re-
apply soap solution. Leakage should not exceed a 1 in. bubble in
5 seconds. If excessive leakage is detected in either test, repair
or replace governor.
4. Test compressor unloader leakage. Drain all air pressure
from system and remove the governor from the compressor.
Temporarily plug the governor unloader port or air line that
mated with, or connected to, the compressor. Build air system
pressure until air dryer purges then IMMEDIATELY SHUT OFF
THE ENGINE. Observe the air gauge in the supply reservoir. If
leakage is within limits, replace the compressor unloaders. Re-
connect the governor to the compressor (after removing plug
installed in governor) and retest while observing supply reservoir
gauge. If excessive leakage is detected, continue testing.
5. Test air dryer purge valve and outlet (delivery) check valve. Drain
all air pressure from 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 system pressure
to governor cut-out and observe air gauge. If little or no pressure
drop is observed replace the air dryer check valve. If pressure
drop continues, apply soap solution to air dryer purge exhaust
and purge control port (where the control line was removed).
Leakage should not exceed a 1 in. bubble in 5 seconds. If
leakage is excessive, repair or replace purge valve assembly.