Bendix Commercial Vehicle Systems AD-9 AND AD-9 IPC AIR DRYERS 4/11 - Manual (Page 25)

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Bendix ® AD-9 ® AND AD-9 ® IPC AIR DRYER TROUBLESHOOTING CHART
SYMPTOMS CAUSE REMEDY
4. Safety valve on air dryer
“popping off” or exhausting
air.
A. Restriction between air dryer and
supply (fi rst) reservoir.
A. Check to determine if air is reaching supply reservoir. Inspect
for kinked tubing or hose. Check for undrilled or restricted hose
or tubing fi ttings and repair or replace as needed.
B. Air dryer safety valve malfunction. B. Verify relief pressure is at vehicle or component manufacturer
specifi cations. Replace if malfunctioning.
C. Desiccant cartridge maintenance
required.
C. Refer to Appendix A ,Table A and column 3. Check compressor
for excessive oil passing and/or correct compressor installation.
Repair or replace as necessary. Replace desiccant cartridge.
D. Malfunctioning discharge check
valve in end cover of the Benidix ®
AD-IP ® air dryer.
D. Test to determine if air is passing through check valve. Repair
or replace.
E. Excessive pressure pulsations
from compressor. (Typical single
cylinder type).
E. Increase volume in discharge line by increasing length or
diameter. Add a ping tank (small reservoir).
F. Governor malfunction. Missing
or restricted governor control line
installation.
F. Test governor operation and/or inspect the control line leading
from the governor UNL (unloader) port to the air dryer control
port.
5. Constant exhaust of air at air
dryer purge valve exhaust.
(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. Refer
to Technical Bulletin TCH-008-040. Repair purge valve as
necessary.
B. Compressor fails to unload (stop
compressing air) and air dryer
purge exhaust makes “sputtering”
or “popping” sound.
B. Confi rm failure to unload by increasing & decreasing engine
RPM and noting change in the rate of leakage and intensity
of accompanying leakage sound. Repair/replace compressor
unloaders.
C. Purge control line connected
to reservoir or exhaust port of
governor.
C. Purge control line must be connected to unloader port of
governor.
D. Purge valve frozen open -
malfunctioning heater and
thermostat, wiring, blown fuse.
D. Test heater and thermostat as described in Preventive
Maintenance Section.
E. Excessive system leakage. E. See Symptom #1.
F. Purge valve stays open - supply air
leaks to control side.
F. Repair purge valve and housing.
6. Can not build system air
pressure.
A. Inlet and outlet air connections
reversed.
A. Connect compressor discharge to air dryer supply port.
Reconnect lines properly.
B. Check valve between air dryer and
fi rst reservoir.
B. Test check valve for proper operation. Repair or replace as
necessary.
C. Kinked or blocked (plugged)
discharge line.
C. Check to determine if air passes through discharge line. Check
for kinks, bends, excessive carbon deposits, or ice blockage.
D. Excessive bends in discharge line
(water collects and freezes)
D. Discharge line should be constantly sloping from compressor
to air dryer with as few bends as possible.
E. Refer to Symptom 4, Causes E &
F.
E. Refer to Symptom #4, Remedies E & F.