Bendix Commercial Vehicle Systems AD-9si Oil Coalescing Air Dryer - Manual (Page 14)

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BENDIX ® AD-9si ™ AIR DRYER
TROUBLESHOOTING CHART
SYMPTOM CAUSE REMEDY
2. Water in vehicle reservoirs. A. Maximum air dryer inlet temperature is
exceeded due to improper discharge
line length.
A. Check for excessive carbon build-up in compressor discharge
line. Replace if required. Make certain that discharge line
length is at least 6 ft. Increase discharge line length and/or
diameter to reduce air dryer inlet temperature.
B. Ambient temperature exceeds 125°F. B. Relocate the air dryer away from excessive heat source.
C. Air system charged from outside
air source (outside air not passing
through air dryer).
C. If system must have outside air fill provision, outside air should
pass through the air dryer.
D. Excessive air usage - Air dryer not
compatible with vehicle air system
requirement (improper air dryer/
vehicle application).
D. Refer to the Bendix ® Air Dryer Application Guideline (BW2600)
for proper application of the Bendix ® AD-9si ™ air dryer. An
extended purge reservoir may be added for higher air usage
vehicles, such as city buses and construction vehicles.
If the vehicle is equipped with high air usage accessories
such as trailer pump-off systems or central tire inflation, the
air for these accessories must by-pass the air dryer.
E. Desiccant requires replacement. E. Replace desiccant cartridge assembly. See Bendix Air Dryer
Application Guideline (BW2600) for recommended service
intervals.
F. Air dryer not purging. F. Refer to Symptom 6.
G. Purge (air exhaust) time insufficient
due to excessive system leakage.
G. Refer to Symptom 1.
3. Safety valve on air dryer
“popping off” or exhausting
air.
A. Safety valve setting too low (<150 psi). A. Replace safety valve.
B. System pressure too high (>135 psi). B. Test with accurate gauge. Replace the governor cartridge if
necessary.
C. Excessive pressure pulsations from
compressor. (Typical single cylinder
type).
C. Increase the volume in the discharge line. This can be
accomplished by adding a 90 cubic inch (or larger) reservoir
between the compressor and the AD-9si air dryer.
4. Constant exhaust of air at air
dryer purge valve exhaust
or unable to build system
pressure. (Charge mode.)
A. Air dryer purge valve leaking
excessively.
A. With compressor loaded, apply soap solution on purge valve
exhaust, to test for excessive leakage. Repair or replace
purge valve as necessary.
B. Purge valve frozen open - faulty heater
and thermostat, wiring, blown fuse.
B. Refer to paragraph 5 of the Operation and Leakage Tests for
heater and thermostat test.
C. Defective AD-9si ™ air dryer delivery
check valve.
C. Refer to Symptom 1, Remedy B.
D. Leaking turbo cut-off valve. D. Repair or replace purge valve assembly.
E. Defective governor. E. Check the governor at both “cut-in” and “cut-out” positions
for proper pressures and excessive leakage at the exhaust.
F. Leaking purge valve control piston
seals.
F. Repair or replace purge valve assembly.