Bendix Commercial Vehicle Systems AD-2 AIR DRYERS 7/04 - Manual (Page 16)

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BW1597 © 2004 Bendix Commercial Vehicle Systems LLC All rights reserved. 7/2004 Printed in U.S.A.
SYMPTOM CAUSE REMEDY
4. Constant exhaust of air A. Air dryer purge valve leaking A. With compressor loaded, apply soap solution
at air dryer purge valve excessively. on purge valve exhaust, to test for excessive
exhaust or unable to leakage. Repair purge valve as necessary.
build system pressure. B. Defective governor. B. Check governor for proper “cut-in”, “cut-out”
pressure and excessive leakage in both
positions. Repair or replace as necessary.
C. Purge control line connected to C. Purge control line must be connected to
reservoir or exhaust port of governor. unloader port of governor.
D. Purge valve frozen open - faulty D. Test heater and thermostat as described in
heater and thermostat, wiring, blown Step 7 of Preventive Maintenance Section.
fuse.
E. Inlet and outlet air connections E. Compressor discharge to inlet port. Reconnect
reversed. lines properly.
F. Check valve between air dryer and first F. Test check valve for proper operation (see
reservoir defective. Symptom #3, Remedy B).
G. Kinked or blocked (plugged) G. Check to determine if air passes through
discharge line. discharge line. Check for kinks, bends,
excessive carbon deposits.
H. Excessive bends in discharge line H. Discharge line should be constantly sloping
(water collects and freezes). from compressor to air dryer with as few bends
as possible.
I. Excessive system leakage. I. See Symptom #1’s Causes and Remedies.
5. Air dryer does not purge A. Broken, kinked, frozen, plugged or A. Test to determine air flows through purge
or exhaust air. disconnected purge control line. control line when compressor unloaded. Check
for undrilled fittings. (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,F,G,H, for Symptom C. Refer to Remedies B, E, F, G, H, for Symptom
#4. #4.
6. Desiccant material being A. This symptom is almost always A. See Causes and Remedies for Symptoms 1,2,3,4
expelled from air dryer accompanied by one or more of and 5.
purge valve exhaust Symptoms 1,2,3,4 and 5. See related
(may look like whitish causes for these Symptoms above.
liquid or paste or small
beads).
B. Air dryer not securely mounted. B. Vibration should be held to minimum. Add
(Excessive vibration). bracket supports or change air dryer mounting
location if necessary.
OR
Unsatisfactory desiccant C. Defective cloth covered perforated C. Replace or rebuild desiccant cartridge. NOTE:
life. plate in air dryer desiccant cartridge If rebuilding cartridge, carefully follow
or improperly rebuilt desiccant instructions packed with cartridge rebuild kit.
cartridge.
D. Compressor passing excessive oil. D. Check for proper compressor installation; if
symptoms persist, replace compressor.
E. Faulty heater and thermostat, wiring, E. Refer to Remedy D under Symptom #4.
fuse not allowing purge. (Cold weather
operation only.)
7. Unable to remove end A. Result of reversing the inlet and outlet A. Refer to Symptom #4, Cause E.
cover, or unable to install connections. (See Symptom #4,
new desiccant cartridge. Cause E.)
8. Air dryer end cover A. Excessive system pressure build up A. Because it is difficult to determine extent of
separates from air dryer within air dryer; caused by either internal damage to air dryer, it is recommended
housing during operation. plugged desiccant, check valve failure, that the air dryer be replaced.
frozen or obstructed discharge line
(between air dryer and first reservoir) or
NOTE: This type of failure can be prevented by
governor failure in conjunction with checking the dryer for proper operation every
safety valve failure. three (3) months.