Section 2
Troubleshooting & Testing
MM-34
Page 12
Revised 11-02
Air leak at turbo
cut-off valve vent.
Lip seal installed upside-down on
piston. Lip must face UP (towards
dryer).
Valve bore worn excessively.
Yes
Yes
Yes
Yes
Install lip seal correctly.
Inspect valve bore for wear. If a new
turbo cut-off valve does not seal in
a clean, lubricated bore, replace the
air dryer.
Air dryer frozen
(water collecting
in base of dryer is
freezing).
No electrical power to heater
connector.
Low voltage to heater connector.
Heater assembly not working.
Wrong voltage air dryer used; i.e.,
12-volt air dryer used in a 24-volt
system.
Yes
Yes
Yes
Yes
Yes
Yes
Yes
Yes
Yes
Yes
Check for a blown fuse. Repair
heater circuit.
NOTE:
There must be power to the
heater connector the entire time the
vehicle’s ignition is
ON
.
Repair cause of low voltage, such
as poor electrical ground, bad
connections, corroded wire splices,
etc.
Replace heater assembly.
Replace with correct voltage air
dryer.
No air pressure
build-up in
system.
Air dryer not plumbed correctly
(connections reversed).
Wrong air line connected to dryer
port 4.
Air governor not working
properly.
Air system leaks, such as
compressor discharge line, air
dryer, reservoirs, brake or
suspension valves, etc.
Air dryer leaks from purge valve.
Yes
Yes
Yes
Yes
Yes
Yes
Yes
Yes
Yes
Yes
Ensure compressor discharge line
is plumbed to air dryer port 1, and
air dryer port 21 is connected to
vehicle’s supply tank.
Ensure dryer port 4 line is
connected to the “UNL” port of the
air governor.
Inspect governor per
manufacturer’s instructions. Repair
or replace as needed.
Locate leak(s) and repair.
Refer to purge valve conditions
listed in this chart.
Water in tanks;
often following
aftermarket
installation or
when dryer is a
replacement for a
competitive brand.
Pressure-controlled check valve
not installed in correct tank or not
installed at all.
Pressure-controlled check valve
properly installed, but one-way
check valve not removed.
Yes
Yes
No
No
Install pressure-controlled check
valve in secondary tank.
Remove one-way check valve so
that only the pressure-controlled
check valve is installed between the
secondary tank and supply tank.
Water, oil, or
sludge in air
system tanks.
Desiccant contaminated with oil.
Yes
Yes
Replace desiccant. Inspect
compressor per manufacturer’s
instructions.
Water in system
tanks, everything
else checks out
okay.
Dryer not suitable for application.
Yes
Yes
Review application guidelines. For
assistance, call ArvinMeritor’s
Customer Service Center at
800-535-5560.
Condition
Possible Cause
Conditions May Occur In:
Solution
Regeneration
Style Air
Dryers
Dedicated
Purge Tank
Air Dryers
