Bendix Commercial Vehicle Systems AD-SP SYSTEM PURGE AIR DRYER 10/04 - Manual (Page 8)

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Notes:
1. Visually check for physical damage to the air dryer
such as chaffed or broken air and electrical lines and
broken or missing parts.
2. Check mounting bolts for tightness. Re-torque to
270–385 in-lbs.
3. Perform the Operation & Leakage Tests listed in this
publication.
This air dryer is intended to remove moisture and other
contaminants normally found in the air brake system.
Do not inject alcohol, anti-freeze, or other de-icing
substances into or upstream of the air dryer. Alcohol
is removed by the dryer, but reduces the effectiveness
of the device to dry air. Use of other substances can
damage the air dryer and may void the warranty.
OPERATION & LEAKAGE TESTS
1. Install a pressure gauge in the #1 reservoir. Check
all lines and fittings leading to and from the air dryer
for leakage and integrity. Test the delivery port check
valve assembly by building the air system to governor
cut-out and observing a test air gauge installed in the
#1 reservoir. Note the pressure on the air gauge after
governor cut-out pressure is reached, a rapid loss of
pressure could indicate a failed delivery port check
valve. This can be confirmed by shutting the engine off,
draining the air brake system pressure to a point below
governor cut-in (typically < 95 psi). Make sure the dryer
has completed the purge cycle (wait 30 seconds after
governor cut-out) and determine if there is any air flow
out of the air dryer purge valve. If air flow is detected
at the purge valve, the air dryer delivery check valve
should be serviced. Remove the test gauge before
returning the vehicle to service.
2. Check for excessive leakage around the purge valve.
With the compressor in loaded mode (compressing
air), apply a soap solution to the purge valve exhaust
port and observe that leakage does not exceed a
one (1) inch bubble in one (1) second. If the leakage
exceeds the maximum specified, repair the purge valve
assembly.
3. Make sure all reservoir drain cocks are closed. Build
up system pressure to governor cut-out and note that
Bendix ® AD-IP ® air dryer purges with an audible escape
of air. Apply and release the service brakes to reduce
system air pressure to governor cut-in. Note that the
system once again builds to full pressure and is
followed by an AD-IP air dryer purge.
4. Check the operation of the end cover heater and
thermostat assembly during cold weather operation as
follows:
A. Electric Power to the Dryer
With the ignition or engine kill switch in the ON
position, check for voltage to the heater and
thermostat assembly using a voltmeter or test
light. Unplug the electrical connector at the air
dryer and place the test leads on each of the pins
of the connector with the locking latch. If there is
no voltage, look for a blown fuse, broken wires, or
corrosion in the vehicle wiring harness. Check to
see if a good ground path exists.
B. Thermostat and Heater Operation
Note: These tests are not required except in cold
weather operation.
Turn off the ignition switch and cool the thermostat
and heater assembly to below 35° F. Using an
ohmmeter, check the resistance between the
electrical pins in the air dryer connector half. The
resistance should be 1.5 to 3.0 ohms for the 12 volt
heater assembly and 6.0 to 9.0 ohms for the 24 volt
heater assembly.
Warm the thermostat and heater assembly to
over 90° F. and again check the resistance. The
resistance should exceed 1000 ohms. If the
resistance values obtained are within the stated
limits, the thermostat and heater assembly is
operating properly. If the resistance values obtained
are outside the stated limits, replace the heater and
thermostat assembly.
REBUILDING THE BENDIX ® AD-IP ® AIR
DRYER
GENERAL
If, after completing the routine operation and leakage tests,
it has been determined that one or more components of
the air dryer requires replacement or maintenance, refer to
the Bendix Quick Reference Catalog (BW1114), available
on www.bendix.com, for the latest maintenance kits and
service parts.
When rebuilding or replacing components of the air dryer
use only genuine Bendix ® service parts.
BENDIX AD-IP AIR DRYER REMOVAL
This air dryer removal process is presented in the event
it becomes necessary to replace the entire air dryer.
Normal service and parts replacement does not require
removal of the air dryer from the vehicle.
1. Park the vehicle on a level surface and prevent
movement by means other than the brakes.