BENDIX AD-IS User's Manual | Page 5

BENDIX Dryer User's Manual - AD-IS.
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may require replacement; however, the following
conditions can also cause water accumulation and
should be considered before replacing the desiccant:

A. An outside air source has been used to charge the

system.  This air did not pass through the drying

B. Air usage is exceptionally high and not normal for a

highway vehicle.

This may be due to accessory air demands or some
unusual air requirement that does not allow the
compressor to load and unload (compressing and
non-compressing cycle) in a normal fashion. Check
for high air system leakage. If the vehicle vocation
has changed it may be necessary to upgrade the
compressor size. Refer to Bendix Specification
BW-100-A, Appendix D to determine if any changes
are necessary.

C. Location of the air dryer and reservoir system is too

close to the air compressor. Refer to Bendix
Specification BW-100-A, Appendix B for discharge
line lengths.

D. In areas where more than a 30 degree range of

temperature occurs in one day, small amounts of
water can temporarily accumulate in the air brake
system due to condensation.  Under these
conditions, the presence of small amounts of
moisture is normal.

Note: A small amount of oil in the system is normal and
should not be considered as a reason to replace the
desiccant cartridge.  Some oil at the dryer exhaust is normal.

2. Visually check for physical damage such as chaffed or

broken air and electrical lines and broken or missing

3. Check the AD-IS® air dryer and purge reservoir bolts for

tightness. See Figure 1.  Re-torque the three air dryer
bolts to 360-420 inch pounds and the four purge reservoir
bolts to 300-360 inch pounds.

4. Perform the Operation & Leakage Tests listed in this



This air dryer and reservoir system  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 and reservoir system.  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 reservoir system and
may void the warranty.


1. Check all lines and fittings leading to and from the air

dryer and reservoir system for leakage and integrity.
Repair any leaks found.

2. Build up system pressure to governor cut-out and note

that the AD-IS® air dryer and reservoir system 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. 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 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 cut-out and note

that the AD-IS® air dryer and reservoir system 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 and reservoir system 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





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