Bendix Commercial Vehicle Systems AD-SP SYSTEM PURGE AIR DRYER 10/04 - Manual (Page 20)

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BENDIX ® AD-IP ® AIR DRYER TROUBLESHOOTING CHART
SYMPTOMS CAUSE REMEDY
1. Air dryer is constantly
“cycling” or purging.
Air dryer purges
frequently (every four
(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 a gauge installed at the RES port of the
governor, pressure should not drop below the “cut-in”
pressure at the onset of the compressor “unloaded”
cycle. If the pressure drops, check for “kinks” or
restrictions in the line connected to the RES port.
The line connected to the RES port on governor must
be the same diameter or preferably larger than the
lines connected to UNL port(s) on governor.
B. Holset ® “E” type compressor. B. Test the Holset ® E Compressor unloader system
with a feedback line and check valve for proper
operation. Make certain the 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