Bendix Commercial Vehicle Systems AD-4 AIR DRYER 10/04 - Manual (Page 15)

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1. Test fittings, 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" bubble in
5 seconds. Reduce system pressure to 80 psi
or less, and re-apply soap solution. Leakage
should not exceed a 1" 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" bubble in 5 seconds. If leakage is
excessive repair or replace purge valve
assembly.
REMEDY CAUSE SYMPTOMS
AD-4 ™ AIR DRYER TROUBLESHOOTING CHART (Continued)