12
BENDIX
®
AD-IS
®
AIR DRYER AND RESERVOIR SYSTEM
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. Air system charged from outside
air source (outside air not passing
through air dryer).
B. If system must have outside air fi ll provision, outside air should
pass through air dryer.
C. Excessive air usage - Air dryer not
compatible with vehicle air system
requirement (Improper air dryer/
vehicle application)
C. Refer to Bendix Advanced Troubleshooting Guide for Air
Brake Compressors (BW1971) for proper application of the
Bendix
®
AD-IS
®
air dryer and reservoir system. An extended
purge model (Bendix
®
AD-IS
®
EP) is available for many 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 infl ation, the
air for these accessories must by-pass the dryer reservoir
system.
D. Desiccant requires replacement.
D. Replace desiccant cartridge assembly.
E. Air by-passes desiccant cartridge
assembly.
E. If vehicle uses Holset compressor, inspect feedback check
valve for proper installation and operation.
F. Air dryer not purging.
F. Refer to Symptom 6.
G. Purge (air exhaust) time insuffi cient
due to excessive system leakage.
G. Refer to Symptom 1.
3. Safety valve on air dryer
“popping off” or exhausting
air.
A. Defective AD-IS air dryer and reservoir
system delivery check valve.
A. Test to determine if air is passing through check valve. Repair
or replace. Refer to Symptom 1, Remedy B.
B. Safety valve setting too low (<150 p.s.i.) B. Replace safety valve.
C. System pressure too high (>135 p.s.i.) C. Test with accurate gauge. Replace governor if necessary.
D. Excessive pressure pulsations from
compressor. (Typical single cylinder
type).
D. Increase volume in discharge line. This can be accomplished
by adding a 90 cubic inch (or larger) reservoir between the
compressor and the AD-IS
®
air dryer and reservoir system.
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.
Refer to Technical Bulletin TCH-008-040.
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-IS 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 governor at both “cut-in” and “cut-out” position for (i)
proper pressures and (ii) excessive leakage at fi ttings and
exhaust.
F. Leaking purge valve control piston
seals.
F. Repair or replace purge valve assembly.
