22
8. Air dryer does not purge
or exhaust air. Note:
this symptom often
precedes Symptom #9
if desiccant cartridge is
not replaced.
A. Air not reaching AD-SP
™
air dryer purge control
port.
B. AD-SP
™
air dryer purge
valve or piston frozen
closed.
C. Extremely high air usage
requirements on vehicle.
AD-SP
™
AIR DRYER TROUBLESHOOTING CHART (Continued)
SYMPTOMS
A. Inspect discharge line installation for water traps
that could freeze. Refer to “Connecting The Air
Lines” section in manual. Repair or replace as
necessary.
B. Test compressor unloader mechanism for
proper operation. Repair or replace as
necessary.
C. Test governor for proper operation. Repair or
replace as necessary.
D. Kinked, plugged, damaged hose tubing or fittings
in line between supply reservoir and low
pressure service reservoir
A. Check that purge control of AD-SP
™
air dryer is
connected to governor UNL (unloader) port on
governor.
B. Inspect for kinked, plugged, damaged hose
tubing or fittings. Check for undrilled or restricted
hose or tubing fittings. Repair or replace as
necessary.
C. Test governor operation. Repair or replace as
necessary.
D. Test compressor unloader mechanism for
proper operation. Repair or replace as
necessary.
E. Check operation of AD-SP
™
air dryer heater and
thermostat. Repair or replace as necessary.
F. Check operation and repair or replace as
necessary.
CAUSE
REMEDY
6. Unable to build air
system pressure. Air
not escaping from
AD-SP
™
air dryer
exhaust (not exhibiting
Symptom #4 plus this
symptom.)
A. Frozen discharge line.
B. Compressor unloader
mechanism
malfunction.
C. Governor malfunction.
D. Air flow to service brake
system restricted or
plugged. Air pressure on
one dash gauge normal
with no, or low pressure
on other gauge.
B. Air trapped in purge
control line (between
governor and AD-SP
™
air
dryer.)
C. Governor malfunction.
7. Unable to build air
system pressure.
A. AD-SP
™
air dryer purge
control line incorrectly
connected to governor.
D. Compressor unloader
mechanism
malfunction.
E. AD-SP
™
air dryer purge
valve piston frozen
open.
F. AD-SP
™
air dryer purge
valve piston stuck.
A. Test to determine air flows through purge control
line to purge control port on AD-SP
™
air dryer
when compressor unloaded. Check for undrilled
fittings. Purge control line broken, not
connected, mis-connected, frozen, damaged.
Inspect, repair or replace as necessary. Replace
desiccant cartridge.
B. Check operation of AD-SP
™
air dryer heater and
thermostat. Repair or replace as necessary.
Replace desiccant cartridge.
C. Refer to the Vehicle Application Requirements
section of this manual and verify application.
