Bendix Commercial Vehicle Systems AD-4 AIR DRYER 10/04 - Manual (Page 14)

14
SYMPTOMS
1. Dryer is constantly
“cycling” or purging.
Dryer purges frequently
(every 4 minutes or less
while vehicle is idling).
A. If leakage IS SHOWN on gauges test for
excessive service brake system leakage.
Allowable leakage:
Single vehicle - 1 psi/minute either service
reservoir.
Tractor trailer - 3 psi/minute either service
reservoir. Repair and retest as required.
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.
CAUSE REMEDY
B. 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.
AD-4 ™ AIR DRYER TROUBLESHOOTING CHART