Bendix Commercial Vehicle Systems AD-SP SYSTEM PURGE AIR DRYER 10/04 - Manual (Page 18)

18
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).
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 the 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.
B. If leakage is NOT SHOWN on gauges test for
excessive supply system leakage.
Remove the drain cock, or valve, in the supply
reservoir (wet tank) and install an air gauge. Build
the system pressure and allow the air dryer to purge.
Observe the air gauge in the supply reservoir. The
pressure drop should not exceed 1 psi per minute.
Perform tests 1 to 6 in the order presented.
Air pressure loss shown on
the dash gauges: test all
components, fittings and lines
in the service brake system
(from this point downstream).
Dash
Gauge
Dash
Gauge