Bendix Commercial Vehicle Systems AD-9 AND AD-9 IPC AIR DRYERS 4/11 - Manual (Page 19)

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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).
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.
A. If leakage IS SHOWN on gauges, test for excessive service
brake system leakage.
Allowable leakage:
Pre-121 vehicles, single vehicles - 2 psi / minute.
Tractor trailer - 3 psi / minute.
121 vehicles, single vehicle - 1 psi / minute per service reservoir.
Tractor trailer - 3 psi / minute per service reservoir. Repair and
retest as required.
If leakage is NOT SHOWN on gauges test for excessive supply
system leakage.
Remove drain cock or valve in supply reservoir (wet tank) and
install air gauge. Build system pressure, allow air dryer to purge
and observe air gauge in supply reservoir. Pressure drop should
not exceed 1 psi per minute.
Perform tests 1 to 6 in the order presented.