Bendix Commercial Vehicle Systems AD-SP SYSTEM PURGE AIR DRYER 10/04 - Manual (Page 21)

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BENDIX ® AD-IP ® AIR DRYER TROUBLESHOOTING CHART
SYMPTOMS CAUSE REMEDY
2. Water and/or oil in
the supply or service
reservoir.
A. Improper discharge line
length or improper line
material. The maximum air
dryer inlet temperature is
exceeded.
A. Refer to Connecting the Air Lines section as well
as Appendix A, Table A columns 1 & 2 then check
line size and length.
B. Air system charged from an
outside air source (outside
air not passing through air
dryer).
B. If the system has an outside air fill provision, outside
air should pass through the air dryer. This practice
should be minimized.
C. Air dryer not purging (see
Symptom #5).
C. See Symptom #5.
D. Purge (air exhaust) time
insufficient due to excessive
system leakage (see causes
for Symptom #1).
D. Check causes and remedies for Symptom #1.
E. Excessive air usage, duty
cycle too high - Air dryer not
compatible with the vehicle
air system requirement
(Improper air dryer/vehicle
application).
Note: Duty Cycle is the ratio
of time the compressor spends
building air to total engine
running time. Air compressors
are designed to build air
(run “loaded”) up to 25% of
the time. Higher duty cycles
cause conditions that affect
air brake charging system
performance which may
require additional maintenance.
Factors that add to the duty
cycle are: air suspension,
additional air accessories,
use of an undersized
compressor, frequent stops,
excessive leakage from fittings,
connections, lines, chambers or
valves, etc.
E. See Appendix A, Table A, column 1, for the
recommended compressor sizes. If the compressor
is “too small” for the vehicle vocation (for example,
where a vehicle’s vocation has changed or service
conditions exceed the original vehicle or engine OE
spec’s) then upgrade the compressor.
Note: The costs incurred (e.g. installing a larger
capacity compressor, etc.) are not covered under
the original compressor warranty.
Charge Cycle Time - The Bendix ® AD-IP ® air dryer
is designed to provide clean, dry air for the brake
system. When a vehicle’s air system is used to
operate non-brake air accessories it is necessary
to determine that; during normal, daily operation the
compressor should recover from governor “cut-in”
to governor “cut-out” (usually 100 psi to 120 psi) in
90 seconds or less at engine RPM’s commensurate
with the vehicle vocation. If the recovery time
consistently exceeds this limit, it may be necessary
to “bypass” the air accessory responsible for the
high air usage. An example of where a by-pass
system would be required is when the compressor
is used to pressurize a tank trailer for purposes of
off-loading product. Consult your local authorized
Bendix parts outlet or sales representative for
additional information.
Purge Cycle Time - During normal vehicle operation,
the air compressor must remain unloaded for a
minimum of 30 seconds. This minimum purge
time is required to ensure complete regeneration
of the desiccant material. If the purge time is
consistently less than the minimum, an accessory
by-pass system must be installed. Consult your
local authorized Bendix ® parts outlet or sales
representative for additional information.