Bendix Commercial Vehicle Systems DRM DRYER RESERVOIR MODULE 3/07 - Manual (Page 5)

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4. Perform the Operation & Leakage Tests listed in this
publication.
WARNING!
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 (ALSO SEE
VIDEO BW2327)
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 cutout and note
that the AD-IS ® 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,
for a single vehicle - 1 psi/minute from either service
reservoir; or for tractor trailer - 3 psi/minute from either
service reservoir, inspect the vehicle air systems for
sources of leakage and repair them. Refer to section
entitled Troubleshooting, Symptoms 1 and 4.
3. Check for excessive leakage around the purge valve
with the compressor in the loaded mode (compressing
air). Apply a soap solution to the purge valve exhaust
port and observe that leakage does not exceed a 1"
bubble in 1 second. If the leakage exceeds the maximum
specified, refer to section entitled Troubleshooting,
Symptom 4.
4. Build up system pressure to governor cutout and note
that the AD-IS ® air dryer purges with an audible burst of
air, followed immediately by approximately 30 seconds
of air flowing out of the purge valve. “Fan” 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-IS
® air dryer purge. If system
does not follow this pattern, refer to section entitled
Troubleshooting, Symptoms 5 and 6.
5. 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 RUN
position, check for voltage to the heater and
thermostat assembly using a voltmeter or testlight.
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 thermostat and
heater assembly to below 40 degrees 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 thermostat and heater assembly to
approximately 90 degrees 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.
6. Pressure protection valves. Observe the pressure gauges
of the vehicle as system pressure builds from zero. The
primary gauge should rise until it reaches approximately
109 psi (±5 psi), then level off (or a momentary slight
fall) as the second pressure protection valve opens
supplying the secondary reservoir. When the secondary
pressure gauge passes through approximately 55 (±5
psi) and then 85 psi (±5 psi) there should be an associated
leveling off (or momentary slight fall) of pressure as the
third and fourth pressure protection valves open. Finally
both the primary and secondary gauges should reach
their full pressure of approximately 130 psi (±5 psi).
If the AD-IS ® air dryer does not perform within the
pressure ranges as described above recheck using
gauges known to be accurate. If the readings remain
outside of the ranges outlined above, replace the
AD-IS
® air dryer. NOTE: There are no kits available for
FIGURE 4 - AD-IS ® AIR DRYER HEATER AND
THERMOSTAT CONNECTOR
HEATER & THERMOSTAT
CONNECTOR