Bendix Commercial Vehicle Systems AD-9si Oil Coalescing Air Dryer - Manual (Page 9)

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1. Visually check for physical damage, such as chafed or
broken air and electrical lines, and broken or missing
parts.
2. Check the Bendix ® AD-9si ™ air dryer and mounting
bolts for tightness. See Figure 1. Re-torque the three
air dryer bolts to 720–912 in-lbs.
3. Perform the Operation & Leakage Tests listed in this
publication.
1. 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 these or other substances can damage the
air dryer and may void the warranty.
2. For the Bendix AD-9si air dryer, there are
no serviceable components or maintenance
requirements that require the removal of the clamp
band.
OPERATION & LEAKAGE TESTS (REFER TO THE
TROUBLESHOOTING CHART IN THIS MANUAL)
1. Check all lines and fittings leading to and from the air
dryer for leakage and integrity. Repair any leaks found.
2. Build up system pressure to governor cut-out and note
that the Bendix AD-9si air dryer purges with an audible
escape of air. Watch the system pressure and note the
pressure fall-off for a ten minute period. If pressure
drop exceeds—a) for a single vehicle: 1 psi/minute
from either service reservoir; or b) for tractor trailer: 3
psi/minute from either service reservoir—inspect the
vehicle air systems for leak sources and repair them.
Refer to the Symptoms 1 and 4 in the Troubleshooting
Chart.
3. CAUTION: Be sure to wear safety glasses in case
of a purge blast. Check for excessive leakage around
the purge valve with the compressor in the charge mode
(compressing air). Apply a soap solution to the purge
valve exhaust port and observe that leakage does not
exceed a 1" bubble in one second. If any leakage
exceeds the maximum specified, refer to Symptom 4
in the Troubleshooting Chart.
4. Build up system pressure to governor cut-out and note
that the AD-9si air dryer purges with an audible burst of
air, followed immediately by approximately 40 seconds
of air flowing out of the purge valve. Apply and release
the service brakes several times to reduce system
air pressure to governor cut-in. Note that the system
once again builds to full pressure and is followed by a
purge. If the system does not follow this pattern, refer
to Symptoms 5 and 6 in the Troubleshooting Chart.
5. Check the operation of the air dryer heater and
thermostat assembly during cold weather operation as
follows:
A. Electric Power to the Dryer (Refer to Figure 4)
With the ignition or engine kill switch in the RUN
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 connections of
the female connector on the vehicle power lead. 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 possible except in cold
weather operation.
Turn off the ignition switch and cool the Heater and
Thermostat assembly to below 40° Fahrenheit.
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 Heater and Thermostat assembly to
approximately 90° Fahrenheit 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.
GENERAL
When rebuilding or replacing components of the air dryer
and reservoir, use only genuine Bendix ® brand replacement
parts. For ease in servicing, the AD-9si air dryer has
been designed so that maintenance kits can be installed
without removing the air dryer from the vehicle. CAUTION:
Always depressurize the air dryer and purge volume
by slowly removing the plug in port 22—and drain
all other reservoirs on the vehicle—to 0 psi before
servicing the air dryer.
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 Maintenance Kit listing shown in this manual or the
Bendix ® Quick Reference Catalog for the appropriate kit(s).
The Quick Reference Catalog (BW1114) can be ordered
and viewed on line at www.bendix.com.
Note: Kits are not available for servicing components inside
the air dryer purge volume.