14
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 the compressor
discharge line. Replace if required. Make certain that the
discharge line length is at least 6 ft. Increase the 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 the 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
Recommended
Service Intervals for Bendix Air Dryers
(BW8068) 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 the compressor loaded, apply a soap solution on the purge
valve exhaust, to test for excessive leakage. Repair or replace
the 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 the
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 the 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 the purge valve assembly.
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