Bendix Commercial Vehicle Systems AD-9 AND AD-9 IPC AIR DRYERS 4/11 - Manual (Page 26)

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Bendix ® AD-9 ® AND AD-9 ® IPC AIR DRYER TROUBLESHOOTING CHART
SYMPTOMS CAUSE REMEDY
7. Air dryer does not purge or
exhaust air.
A. Missing, broken, kinked, frozen,
plugged or disconnected purge
control line.
A. Inspect control line from governor UNL (unloader) port to control
port of air dryer. Test to determine if air fl ows through purge
control line when compressor unloaded. Check for undrilled
fi ttings. (See Symptom #4, Remedy C.)
B. Faulty air dryer purge valve. B. After determining air reaches purge valve (Remedy A above),
repair purge valve.
C. See Causes, B, E, G for Symptom
#4.
C. Refer to Remedies B, E, G for Symptom #4.
8. Desiccant material being
expelled from air dryer purge
valve exhaust (may look like
whitish liquid or paste or
small beads.)
- OR -
Unsatisfactory desiccant life.
A. This symptom is almost always
accompanied by one or more of
Symptoms 1, 2, 3, 4 and 5. See
related causes for these symptoms
above.
A. See Causes and Remedies for Symptoms 1, 2, 3, 4 and 5.
B. Air dryer not securely mounted.
(Excessive vibration.)
B. Vibration should be held to minimum. Add bracket supports or
change air dryer mounting location if necessary.
C. Malfunctioning or saturated
desiccant cartridge.
C. Replace desiccant cartridge assembly.
D. Compressor passing excessive oil. D. Check for proper compressor installation; if symptoms persist,
replace compressor.
E. Desiccant cartridge not assembled
properly to end cover. (Loose
attachment)
E. Check the torque on the desiccant cartridge
to end cover attachment. Refer to assembly section of this
data sheet.
9. “Pinging” noise excessive
during compressor loaded
cycle.
A. Defective check valve assembly in
air dryer end cover.
A. Refer to Remedy C, Symptom #1.
B. Leaking Turbo Cut-off valve. B. Repair or replace purge valve assembly.
C. Leaking purge valve control piston
o-ring.
C. Repair or replace purge valve assembly.
10. Constant seepage of air at
air dryer purge valve exhaust
(non-charging mode.)
A. Defective check valve assembly in
air dryer end cover.
A. Refer to Remedy C, Symptom #1.
B. Leaking Turbo Cut-off valve. B. Repair or replace purge valve assembly
C. Leaking purge valve control piston
o-ring.
C. Repair or replace purge valve assembly.
11. The air dryer purge piston
c y c l e s r a p i d l y i n t h e
compressor unloaded (non-
compressing) mode.
A. Compressor fails to “unload”. A. Faulty governor installation; no air line from governor to
compressor or line is kinked or restricted. Install or repair air
line.