Bendix Commercial Vehicle Systems AD-SP SYSTEM PURGE AIR DRYER 10/04 - Manual (Page 24)

24
BENDIX ® AD-IP ® AIR DRYER TROUBLESHOOTING CHART
SYMPTOMS CAUSE REMEDY
5. Constant exhaust
of air at air dryer
purge valve exhaust.
(Charge mode.)
A. Air dryer purge valve is
leaking excessively.
A. With the compressor loaded, apply a soap solution
on the purge valve exhaust, to test for excessive
leakage. Refer to Technical Bulletin TCH-008-040.
Repair the purge valve as necessary.
B. Compressor fails to unload
(stop compressing air) and
the air dryer purge exhaust
makes “sputtering” or
“popping” sound.
B. Confirm the 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 the heater and thermostat as described in
Preventative Maintenance Section.
E. Excessive system leakage. E. See Symptom #1.
F. Purge valve stays open -
supply air leaks to control
side.
F. Repair the purge valve and housing.
6. Can not build system
air pressure.
A. Inlet and outlet air
connections reversed.
A. Connect compressor discharge to the air dryer
supply port. Reconnect the lines properly.
B. Check valve between the air
dryer and first reservoir.
B. Test the 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 the
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
the compressor to the air dryer with as few bends
as possible.
E. Refer to Symptom 4, Causes
E & F.
E. Refer to Symptom #4, Remedies E & F.
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 the governor UNL
(unloader) port to control port of air dryer. Test to
determine if air flows through purge control line
when compressor unloaded. Check for undrilled
fittings. (See Symptom #4, Remedy C.)
B. Faulty air dryer purge valve. B. After determining the air reaches the purge valve
(Remedy A above), repair the purge valve.
C. See Causes, B, E, G for
Symptom #4.
C. Refer to Remedies B, E, G for Symptom #4.