Bendix Commercial Vehicle Systems AD-9 AND AD-9 IPC AIR DRYERS 4/11 - Manual (Page 21)

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Bendix ® AD-9 ® AND AD-9 ® IPC AIR DRYER TROUBLESHOOTING CHART
SYMPTOMS CAUSE REMEDY
1. Dryer is constantly “cycling”
or purging. Dryer purges
frequently (every 4 minutes
or less while vehicle is idling)
(continued).
A. Excessive system leakage.
IMPORTANT: Note whether air
pressure loss is shown on dash
gauge(s). Pressure loss shown on
gauges is caused by service brake
system or component leakage.
Pressure loss NOT SHOWN
on gauges is caused by supply
system or component leakage.
(continued)
6. With gauge installed at RES port of governor, pressure should
not drop below ”Cut-In” pressure at the onset of the compressor
“Unloaded” cycle. If pressure drops, check for “kinks” or
restrictions in line connected to RES port. Line connected to
RES port on governor must be same diameter, or preferably
larger than, lines connected to UNL port(s) on governor.
B. Leaking purge valve housing
assembly and/or o-rings in air
dryer end cover.
B. With the supply port open to atmosphere, apply 120 psi at the
control port. Apply a soap solution to the supply port and exhaust
port (purge valve seat area). Permissible leakage - 1" bubble in
5 seconds.
C. Holset ® “E” type compressor. C. Test the Holset ® E Compressor unloader system with feedback
line and check valve for proper operation. Make certain Holset
ECON is not in use with the drop-in version of the air dryer, if
so, remove and retest.
When installing a Bendix Drop-In air dryer in a system equipped
with a Holset E or QE compressor, remove the Holset ECON valve
along with its feedback and governor control line.
Typical Drop-In Air Dryer End Cover
Check Valve
Feedback Line