BENDIX SD-08-2418 User manual

1
Bendix®AD-IS®& AD-IS®PuraGuard®(Oil Coalescing) Air Dryer &
Reservoir Systems
Desiccant Cartridge
(PuraGuard® oil coalescing shown)
Purge
Reservoir
24
AUX 1
Auxiliary
Delivery
Ports (4)
Governor
Heater
Thermostat
Safety
Valve
Air Dryer
Part Number
Stamped
Here
Mounting
Bolts (3)
22
SEC
Delivery to
Secondary
Reservoir
21
PRI
Delivery to
Primary
Reservoir
Pressure
Protection
Valves (4)
SD-08-2418
Mounting
Holes (4)
1
IN
Supply from
Compressor
UNL
Governor
Unloader (2)
EXH
Governor
Exhaust
23
AUX 2
Auxiliary
Delivery
Port
Pressure
Protection
Valves (4)
Purge Valve
RES
Governor
Reservoir (2)
Figure 1 - Bendix® AD-IS®& AD-IS®PuraGuard®Oil Coalescing Air Dryer & Reservoir Systems
Desiccant
Cartridge
(standard shown)
PuraGuard Medallion
(located on the top of the
air dryer cartridge)
OE and Service New Bendix®AD-IS®purge
valves, manufactured after December 2014,
contain two parallel ribs on the side of the body
as shown above. These ribs identify the purge
valve as a genuine Bendix®product. If the OE
or Service New air dryer or purge valve being
serviced was manufactured after this date and
does not contain these ribs, it is not a genuine
Bendix product.

2
GENERAL SAFETY GUIDELINES
WARNING! PLEASE READ AND FOLLOW THESE INSTRUCTIONS
TO AVOID PERSONAL INJURY OR DEATH:
When working on or around a vehicle, the following guidelines should be observed AT ALL TIMES:
▲Park the vehicle on a level surface, apply the
parking brakes and always block the wheels.
Always wear personal protection equipment.
▲Stop the engine and remove the ignition key
when working under or around the vehicle.
When working in the engine compartment,
the engine should be shut off and the ignition
key should be removed. Where circumstances
require that the engine be in operation, EXTREME
CAUTION should be used to prevent personal
injury resulting from contact with moving,
rotating, leaking, heated or electrically-charged
components.
▲Do not attempt to install, remove, disassemble
or assemble a component until you have read,
and thoroughly understand, the recommended
procedures. Use only the proper tools and
observe all precautions pertaining to use of those
tools.
▲If the work is being performed on the vehicle’s
air brake system, or any auxiliary pressurized air
systems, make certain to drain the air pressure
from all reservoirs before beginning ANY work
on the vehicle. If the vehicle is equipped with a
Bendix®AD-IS®air dryer system, a Bendix®DRM™
dryer reservoir module, or a Bendix® AD-9si®air
dryer, be sure to drain the purge reservoir.
▲Following the vehicle manufacturer’s
recommended procedures, deactivate the
electrical system in a manner that safely removes
all electrical power from the vehicle.
▲Never exceed manufacturer’s recommended
pressures.
▲Never connect or disconnect a hose or line
containing pressure; it may whip and/or cause
hazardous airborne dust and dirt particles. Wear
eye protection. Slowly open connections with
care, and verify that no pressure is present. Never
remove a component or plug unless you are
certain all system pressure has been depleted.
▲Use only genuine Bendix®brand replacement
parts, components and kits. Replacement
hardware, tubing, hose, fi ttings, wiring, etc. must
be of equivalent size, type and strength as original
equipment and be designed specifi cally for such
applications and systems.
▲Components with stripped threads or damaged
parts should be replaced rather than repaired.
Do not attempt repairs requiring machining or
welding unless specifi cally stated and approved
by the vehicle and component manufacturer.
▲Prior to returning the vehicle to service, make
certain all components and systems are restored
to their proper operating condition.
▲For vehicles with Automatic Traction Control
(ATC), the ATC function must be disabled (ATC
indicator lamp should be ON) prior to performing
any vehicle maintenance where one or more
wheels on a drive axle are lifted off the ground
and moving.
▲The power MUST be temporarily disconnected
from the radar sensor whenever any tests USING
A DYNAMOMETER are conducted on a vehicle
equipped with a Bendix® Wingman®system.
▲You should consult the vehicle manufacturer's operating and service manuals, and any related literature,
in conjunction with the Guidelines above.

3
DESCRIPTION
The function of both the Bendix®AD-IS®(Integrated Solution
Air Dryer)air dryer & reservoir system, and the Bendix®
AD-IS®PuraGuard®oil coalescing air dryer & reservoir
system, is to collect and remove air system contaminants
in solid, liquid, and aerosol form before they enter the brake
system. As a module, they provide heavy vehicles with an
integrated vehicle air dryer, purge reservoir, governor, and
a number of the charging valve components in a complete
assembly. These components have been designed as an
integrated air supply system.
Both air dryer & reservoir systems provide clean, dry air
to the components of the brake system – which increases
the life of the system and reduces maintenance costs.
The need for daily manual draining of the reservoirs is
eliminated.
The Bendix AD-IS PuraGuard oil coalescing air dryer has
an identical appearance to the standard Bendix AD-IS air
dryer with one exception– it contains a coalescing media at
the inlet of the desiccant bed and an identifying medallion
on the top (See Figure 1). The coalescing media provides
a higher level of oil removal over the standard AD-IS air
dryer. The AD-IS PuraGuard oil coalescing air dryer has
all of the same functions as the standard AD-IS air dryer
and is used in applications where lower oil concentration
levels are required.
IMPORTANT
When servicing, note that standard AD-IS air dryers or
air dryer cartridges may be serviced with PuraGuard oil
coalescing air dryers or cartridges, however, PuraGuard oil
coalescing air dryers or cartridges must only be serviced
with like replacements.
Note: Unless otherwise stated in this manual, AD-IS air
dryer & reservoir systems refers to both the standard and
the PuraGuard oil coalescing air dryer & reservoir systems.
The function of the pressure protection valves is to protect
each reservoir from a pressure loss in the other reservoir or
a pressure loss in an air accessory. Each of the pressure
protection valves in the AD-ISair dryer & reservoir systems
may have different pressure settings. These are factory set
and must not be changed or adjusted.
The air dryer & reservoir system consists of a spin on
desiccant cartridge secured to a base assembly. The
base assembly contains a delivery check valve assembly,
safety valve, heater and thermostat assembly, pressure
protection valves, threaded air connections, and the purge
valve assembly.
Table 1 – Port Designations
Air Connection
Port ID
Function/
Connection Qty.
1
IN Inlet Port (air in) 1
21
PRI
Delivery Port Out (to Primary
Reservoir) 1
22
SEC
Delivery Port Out (to Secondary
Reservoir) 1
24
AUX 1 Auxiliary Delivery Port (air out) 4
23
AUX 2 Auxiliary Delivery Port (air out) 1
UNL Unloader Control Air
(Bendix®D-2A™Governor) 2
RES Common Reservoir Pressure
(D-2A Governor) 2
EXH Governor Exhaust 1
The removable purge valve assembly incorporates the
purge valve mechanism and a turbocharger cut-off feature
that is designed to prevent loss of engine turbo boost
pressure during the purge cycle of the Bendix AD-IS air
dryer & reservoir system. For ease of maintenance, all
replaceable assemblies can be serviced without removal
of the air dryer & reservoir system from its mounting on
the vehicle. Refer to the Preventive Maintenance section.
BENDIX AD-IS AIR DRYER & RESERVOIR
SYSTEM OPERATION: GENERAL
(Refer to Figure 2.)
The Bendix AD-IS air dryer & reservoir systems are
designed to receive compressed air from the vehicle air
compressor, clean and dry the air, deliver air to the vehicle’s
primary reservoir, secondary reservoir and accessories,
and control the compressor/dryer charge cycle.
The AD-IS air dryer & reservoir system alternates between
two modes, or cycles, during operation: the Charge Cycle
and the Purge Cycle.What follows describes these cycles
of operation.

4
Figure 2 - Bendix® AD-IS®Air Dryer & Reservoir System Charge Cycle
CHARGE CYCLE (Refer to Figure 2.)
When the compressor is running loaded (compressing air),
compressed air ows through the compressor discharge
line to the inlet (1/IN) port of the air dryer body. The
compressed air often includes contaminates such as oil,
oil vapor, water, and water vapor.
Traveling through the discharge line and into the air dryer,
the temperature of the compressed air falls, causing
some of the contaminants to condense and drop to the
bottom of the air dryer and purge valve assembly. These
contaminants are ready to be expelled at the next purge
cycle. The air then ows into the desiccant cartridge,
where it ows through an oil separator – or coalescing
lter if equipped with a Bendix®PuraGuard®oil coalescing
cartridge – which removes water in liquid form, as well as
liquid oil and solid contaminants.
Air then ows into the desiccant drying bed and becomes
progressively drier as water vapor adheres to the desiccant
material in a process known as adsorption.
Dry air exits the desiccant cartridge, through the center
of the base assembly, then ows to the delivery check
valve, through an orice, and into the purge reservoir. The
delivery check valve opens, supplying air to the pressure
protection valves (A) through (D) simultaneously, the
safety valve, and also to the reservoir port of the attached
governor. The purge reservoir lls, storing air that will be
used to regenerate the desiccant during the purge cycle.
This air is available to supply downstream components
during the charge mode.
When the air pressure reaches approximately 106 psi, the
four pressure protection valves will open and air will be
supplied to the primary reservoir, secondary reservoir, and
Compressor
Governor
Desiccant
Bed
Delivery
Check
Valve
(open)
Primary
Port (PRI)
Purge
Valve
(closed) Turbo
Cut-Off
Valve
(open)
Engine
Turbo
Unloader
Port
Supply
Port
Primary
Reservoir
Pressure
Protection
Valves
Auxiliary Ports
(To Accessories)
See
Note 1
Safety
Valve Purge
Reservoir
Drain Valve
Secondary
Reservoir
Secondary
Port
(SEC)
Purge
Reservoir
Purge
Orice
Oil Coalescing Filter
(Bendix®AD-IS®
PuraGuard®oil
coalescing air dryer)
AD
C
B
Purge
Control
Channel
Diagram shows all pressure
protection valves open.

5
Similarly, the governor also supplies air pressure to the
air dryer. The pressure also moves the air dryer purge
piston down, opening the purge valve to atmosphere
and closing off the compressor air supply to the turbo
cut-off valve (covered in the Turbo Cut-off Valve section
of this document). Water and contaminants captured are
expelled immediately when the purge valve opens. In
addition, air – which was owing through the desiccant
cartridge – changes direction and begins to ow toward
the open purge valve. Contaminants collected by the air
dryer are removed by air owing from the purge reservoir
through the desiccant drying bed to the open purge valve.
The initial purge and desiccant cartridge decompression
lasts only a few seconds, evidenced by an audible burst
of air at the air dryer exhaust.
Figure 3 - Bendix® AD-IS®Air Dryer & Reservoir System Purge Cycle
Diagram shows all pressure
protection valves open.
Compressor
Governor
Desiccant
Bed
Delivery
Check
Valve
(open)
Primary
Port (PRI)
Purge
Valve
(Open) Turbo
Cut-Off
Valve
(Closed)
Engine
Turbo
Unloader
Port
Supply
Port
Primary
Reservoir
Pressure
Protection
Valves
Exhaust
Safety
Valve Purge
Reservoir
Drain Valve
Secondary
Reservoir
Purge
Orice
Oil Coalescing Filter
(Bendix®AD-IS®
PuraGuard®oil
coalescing air dryer)
AD
C
B
Purge
Control
Channel
accessories. If the pressure protection valves are pre-set
to different values, the valves will open– in order of lowest
setting to highest setting – when charging a at system.
The air dryer and purge reservoir will remain in the charge
cycle until the air brake system pressure builds to the
governor cut-out setting of approximately 130 psi.
PURGE CYCLE (Refer to Figure 3.)
When air brake system pressure reaches the cut-out setting
of the governor, the governor unloads the compressor
activating the purge cycle of the air dryer & reservoir.
The governor unloads the compressor by allowing air
pressure to ll the line leading to the compressor unloader
mechanism. This suspends the delivery of compressed air
to the Bendix® AD-IS®air dryer & reservoir system.
Auxiliary Ports
(To Accessories)
Secondary
Port (SEC)
Purge
Reservoir

6
The actual regeneration of the desiccant drying bed begins
as dry air from the purge reservoir then ows through the
purge orice into the desiccant bed. Pressurized air from
the purge reservoir expands after passing through the
purge orice; its pressure lowers and its volume increases.
The ow of dry air through the drying bed regenerates the
desiccant material by removing any water vapor adhering to
it. See Table 2 for the time required for the entire contents
of the purge reservoir of a Bendix®AD-IS®air dryer &
reservoir system to ow through the desiccant drying bed.
The delivery check valve assembly prevents air pressure
in the brake system from returning to the air dryer during
the purge cycle. The air dryer remains in the purge mode
until the air system pressure drops below the governor
cut-in pressure thereby placing both the compressor and
the air dryer in the charge mode. After the purge reservoir
pressure is depleted, the air dryer desiccant has been
regenerated and is now ready for the next charge cycle.
TURBO CUT-OFF VALVE (Refer to Figure 3)
The primary function of the turbo cut-off valve is to prevent
loss of engine turbocharger air pressure through the
AD-IS air dryer when the dryer is in the purge mode.
At the onset of the purge cycle, the downward travel of the
purge piston is stopped when the turbo cut-off valve (the
tapered portion of the purge piston) contacts its mating
metal seat in the purge valve housing. With the turbo
cut-off valve seated (in the closed position), air in the
compressor discharge line – as well as the AD-IS air dryer
inlet port – cannot enter the air dryer. By completing these
actions, the turbo cut-off effectively maintains turbo charger
boost pressure to the engine.
PREVENTIVE MAINTENANCE
Important: Review the warranty policy before performing
any intrusive maintenance procedures. An extended
warranty may be voided if intrusive maintenance is
performed during this period. Purge valve maintenance
is permissible during the warranty period only when using
a genuine Bendix®purge valve kit.
Because no two vehicles operate under identical
conditions, maintenance and maintenance intervals will
vary. Experience is a valuable guide in determining the best
maintenance interval for any one particular operation.
Bendix®AD-IS®Air Dryer Purge Reservoir Size and Purge Time
AD-IS Air Dryer Purge
Reservoir Options Description Purge Reservoir Size (in3)
Approximate Purge Time
(See Note 2)
4"
AD-IS air dryer
with standard purge volume 200 in335 seconds
6"
AD-IS air dryer with extended
purge volume 300 in355 seconds
4"
AD-IS air dryer with standard
purge volume and extended purge
volume mounted remotely
200 in3(standard purge)
+
288 in3 (remote purge)
=
488 in3total volume
(See Note 1)
85 seconds
Note 1: The remote purge reservoir volume can vary based on vehicle manufacturer options. Purge time is directly related to the purge
reservoir volume, the larger the purge volume the longer the time needed to purge.
Note 2: Purge times are approximate and based on a new system with minimal leakage.
Table 2 - Purge Volume Size and Purge Time

7
Recommended Service Intervals for Bendix AD-IS Air Dryers
Air
Usage Typical Vehicle Vocation Axles
*Reservoir Drain Interval
(whichever comes first)
Bendix
Standard
Cartridge
Replacement
PuraGuard®Oil Coalescing
Cartridge ReplacementHours Mileage Time
Standard Line haul, city, delivery 5 or
less 900 25,000 3 months 36 months 24 months or 200,000 miles
Medium
Double trailers,
light transit,
light off-highway
8 or
less 450 12,000 2 months 24 months 18 months or 150,000 miles
High
Multiple trailers,
city transit,
heavy duty off-road
11 or
less 300 6,000 1 month 12 months 12 months
*Change the desiccant cartridge more frequently if more than just traces of moisture are found in any of the reservoirs when draining them.
Table 3 - Service Intervals
RESERVOIR DRAINING
1. Per the guidelines shown in Table 3, check for moisture
in the air brake system by opening reservoir drain
valves and checking for the presence of water. If
moisture is present, the desiccant cartridge 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 bed.
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. For assistance contact the Bendix
TechTeam at 1-800-AIR-BRAKE, (1-800-247-2725,
option 2) or bendix.com.
C. The location of the air dryer & reservoir system is too
close to the air compressor. For assistance contact
the Bendix TechTeam at 1-800-AIR-BRAKE, (1-800-
247-2725, option 2) or bendix.com.
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.
CARTRIDGE REPLACEMENT
Adhering to a preventive maintenance schedule is crucial to
keeping a vehicle’s air system clean and ensuring superior
performance of all components that utilize system air – such
as brakes, emissions equipment, and automated manual
transmissions. See Table 3 for Bendix®AD-IS®air dryer
recommended cartridge replacement intervals for vehicles
equipped with a Bendix®compressor.
More frequent intervals may be required depending on
the vehicle’s age, its compressor condition, use of a
non-Bendix compressor, the operating environment, the
vehicle’s vocation, and its usage. In conjunction with these
guidelines, eets can determine the functionality of their
lters by checking for moisture in the air brake system
monthly. If moisture is present, the air dryer cartridge may
require replacement.
1. Visually check for physical damage, such as chafed or
broken air and electrical lines, and broken or missing
parts.
2. 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 in-lbs and the four purge reservoir
bolts to 300-360 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
& 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 may void the warranty.

8
OPERATION & LEAKAGE TESTS (REFER TO
THE TROUBLESHOOTING CHART IN THIS
MANUAL)
For additional information see video BW2327 – available
through the Document Library on bendix.com.
1. Check all lines and ttings leading to and from the
air dryer & reservoir system for leakage and integrity.
Repair any leaks found.
2. Build up system pressure to governor cut-out and note
that the Bendix®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 – 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
Symptoms 1 and 4 in the Troubleshooting Chart.
3. 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 specied, refer to Symptom 4
in the Troubleshooting Chart.
4. Build up system pressure to governor cut-out and note
that the AD-IS air dryer purges with an audible burst of
air, followed immediately by air owing out of the purge
valve. See Table 2 for the time required for the entire
contents of the purge reservoir of a Bendix AD-IS air
dryer & reservoir system to ow through the desiccant
drying bed. 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 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 end cover 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 &
reservoir system 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.
Figure 4 - Heater and Thermostat Connector
Heater &
Thermostat
Connector
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°F. Using an
ohmmeter, check the resistance between the
electrical pins in the air dryer & reservoir system
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°F and check the resistance
again. 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 or secondary gauge should rise until
it reaches approximately 106 psi (±6 psi), then level
off (or a momentary slight fall) as the next pressure
protection valve opens – supplying its reservoir. When
that pressure gauge passes through approximately 106
psi (±6 psi) there should be an associated leveling off (or
momentary slight fall) of pressure as the third and fourth
pressure protection valves open. Then the primary and
secondary gauges should increase together until they
reach their full pressure of approximately 130 psi (±5
psi).

9
3. 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 a
purge at the air dryer exhaust.
4. It is recommended that the total air system be tested for
leakage to ensure that the AD-IS air dryer & reservoir
system will not cycle excessively.
BRAKING SYSTEM PROTECTION
The Bendix AD-IS air dryer allows the system to maintain
one brake circuit, up to about 100 psi, even after a pressure
loss in the other brake circuit. This allows a vehicle to
be moved (in an emergency), but with reduced braking
capacity. Compare this to a conventional system, where a
loss of pressure in one service tank leaves the vehicle with
a limited number of reduced braking capacity applications
before the parking brakes automatically apply and stay on.
See Bendix publication BW5057 "Air Brake Handbook."
Figure 5 - Pressure Protection Valve Locations
Pressure Protection
Valve Locations
Bendix®AD-IS®Air
Dryer Governors Are
Non-adjustable
(feature a breather valve
in this port)
WARNING
DO NOT ATTEMPT TO ADJUST OR
SERVICE THE PRESSURE PROTECTION
VALVES. INCORRECT PRESSURE
PROTECTION VALVE SETTINGS CAN
RESULT IN AUTOMATIC APPLICATION
OF VEHICLE SPRING BRAKES WITHOUT
PRIOR WARNING.
If the Bendix®AD-IS®air dryer & reservoir system 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,
replace the AD-IS air dryer & reservoir system. NOTE:
There are no kits available for the servicing of the
pressure protection valves.
Do not attempt to adjust or service the pressure
protection valves – incorrect pressure protection valve
settings can result in the automatic application of the
vehicle spring brakes without prior warning (in the event
one of the supply circuits experiences rapid pressure
loss).
GENERAL
When rebuilding or replacing components of the air dryer
& reservoir, use only genuine Bendix®brand replacement
parts. For ease in servicing, the AD-IS air dryer & reservoir
have been designed so that maintenance kits can be
installed without removing the air dryer & reservoir from
the vehicle.
Always depressurize the air dryer and purge reservoir – and
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 bendix.com.
Note: Kits are not available for the servicing of the pressure
protection valves (See Figure 5). Do not attempt to adjust
or service the pressure protection valves – these are not
service items.
TESTING THE BENDIX®AD-IS®AIR DRYER
& RESERVOIR SYSTEM
Before placing the vehicle into service, perform the
following tests:
1. Close all reservoir drain valves.
2. Build up system pressure to governor cut-out and note
that the Bendix AD-IS air dryer purges (with an audible
burst of air), followed immediately by air owing out of
the purge valve. This purge time is related to the purge
volume as shown in Table 2.

10
ROADSIDE INSPECTION
In the event of a roadside inspection the system behavior
will be as follows: When the system is charged to
governor cut-out and then one reservoir drain valve is
opened, initially both reservoir gauges will fall; however,
the Bendix®AD-IS®air dryer primary and secondary
pressure protection valves will close at pressures above
70 psi, protecting the remaining brake circuit from further
loss of pressure.
TEMPORARY AIR DRYER & RESERVOIR SYSTEM
BYPASS
To temporarily bypass the air dryer, follow these procedures:
Adhere to the General Safety Guidelines outlined
elsewhere in this document.
Make sure that all residual pressure has been released and
the air dryer purge reservoir has been drained to 0 psi,
then remove the air supply line from the compressor to the
inlet port (1/IN). Remove the safety valve from the Bendix
AD-IS air dryer (see Figure 1 for location). Note that a short
puff of trapped air may vent from the safety valve port when
removing the valve. Install a T-tting into the port. Using
any adapters necessary, reinstall the safety valve in one of
the branches of the T-tting. Using any adapters necessary,
install the air supply line into the remaining T-tting port.
After testing the T-tting for any air leakage – by using a
soap solution after charging to system cut-out pressure (a
1” bubble in 10 seconds is acceptable) – the vehicle may
be returned to temporary service.
Note: This is a temporary bypass of the air dryer. Full
repair of the unit must be carried out at the earliest
opportunity.
With the air dryer removed from the system, contaminants
will be entering the air brake system: reservoirs will need to
be manually drained daily until the repairs are completed.
At the end of each working day, park the vehicle and slowly
drain pressure through the drain valves – leave open to
the atmosphere – for several hours, if possible. When
repairs are carried out, be sure to check that all reservoirs
(including the air dryer purge reservoir) are emptied of all
contaminants.
If, after bypassing the air dryer & reservoir system, the
system pressure still does not build, use the following
procedure to remove, clean, and reinstall the delivery
check valve.
DELIVERY CHECK VALVE CLEANING PROCEDURE
(Note: This is only required if system pressure does not
build after temporary bypass is completed.)
Refer to Figure 6 throughout the following procedures.
Depressurize the air brake system following the General
Safety Guidelines outlined elsewhere in this document.
Also, always depressurize the air dryer purge reservoir
before servicing the air dryer.
This procedure does not require removal of the Bendix
AD-IS air dryer & reservoir from the vehicle.
1. Remove the line from the governor and mark for easy
reinstallation.
2. Remove the bolts attaching the governor to the AD-IS
air dryer & reservoir system and retain for reassembly.
3. Remove the governor from the air dryer. Be aware that
a short puff of trapped air may vent when the governor is
removed. Retain the governor gasket for reassembly if
a new governor gasket is not available. Remove and
retain the o-ring from the adapter.
4. The spring / delivery check valve can now be removed.
5. Remove and retain the o-ring from the check valve
body.
Maintenance Kits
Kit Description Piece No.
Delivery Check Valve Replacement Kit 5004052
Desiccant Cartridge Replacement Kit (Standard) 5008414
Desiccant Cartridge Replacement Kit - Bendix
®
AD-IS
®
PuraGuard
®
air dryer (can be used to
replace the standard cartridge)
5008414PG
Drain Valve 5004961N
Governor and Check Valve Replacement Kit 5004049
Governor Gasket 5007834
Heater & Thermostat Replacement (12 volt) 109495
Heater & Thermostat Replacement (24 volt) 109496
Bendix
®
PuraGuard
®
Oil Coalescing Desiccant
Cartridge Service New Kit K020366
Mounting Bolt Kit 5009233
Protective Boots (for pressure protection valves) 5005163
Safety Valve 800350
Splash Shield Kit (includes bracket and cover) K052469
Splash Shield Cover 5005266N
Silencer Kit K021189
Wiring Harness & Splice Kit 109871N
Purge Valve
Assembly Type Configuration
Service
Kit Pc. No.
Purge Valve Assembly for
climate conditions above
-40°C (-40°F)
Bendix
®
AD-IS
®
Air Dryer K022105
AD-IS
®
EverFlow
®
Module K031560
AD-IS
®
Discharge
Line Unloader K031562
Arctic Purge Valve Assembly
for climate conditions of
-40°C to -50°C
(-40°F to -58°F)
AD-IS
®
Air Dryer K031559
AD-IS
®
EverFlow
®
Module K031561
AD-IS
®
Discharge
Line Unloader K031563

11
Figure 6 - Bendix® AD-IS®Air Dryer & Reservoir System Delivery Check Valve
Governor Gasket
(special gasket,
see assembly note 6)Governor
(non-adjustable,
130 psi cut-out)
Bolts
Adapter
Large
O-ring
Spring
Check
Valve
Body
Small
O-ring
CLEANING & INSPECTION
1. Use a suitable solvent to clean all metal parts, and
use a cotton swab to clean the bore (Note: Do not use
abrasives or tools to clean the bore: any scratches
caused may necessitate replacing the Bendix®
AD-IS® air dryer & reservoir system.) Superficial
external corrosion and/or pitting is acceptable.
2. Clean the o-rings with a clean dry cloth. Do not use
solvents.
3. Inspect for physical damage to the bore and the check
valve seat. If the bore is damaged (by scratches,
etc. that would prevent the delivery check valve from
seating), replace the AD-IS air dryer.
4. Inspect the delivery check valve, o-rings, etc. for wear or
damage. Replace, if necessary, using the check valve
replacement kit available at any authorized Bendix®
parts outlets.
5. Inspect all air line ttings for corrosion and replace as
necessary.
ASSEMBLY
1. Lubricate the smaller o-ring and check valve body with
a heavy-duty lithium grease.
2. Install this o-ring on the check valve body by sliding the
o-ring over the set of four tapered guide lands. The
o-ring groove holds the o-ring in its correct location.
3. At the other end of the check valve body, the spring is
installed over the set of four straight guide lands. When
the spring has been pushed to the correct location, the
check valve body is designed to hold the end of the
spring in position: be sure that the spring is not loose
before continuing with this installation.
4. Install the assembled check valve body/o-ring/spring
into the delivery port so that the o-ring rests on its seat
and the free end of the spring is visible.
5. Grease the adapter and the remaining larger o-ring and
install it onto the tting.
6. Position the governor gasket, then insert the governor
mounting bolts through the governor and tighten (to
125 in-lbs). Note: Do not replace with a standard
compressor/governor gasket.
7. Re-attach the line to the governor.
8. Before placing the vehicle back into service, check
to see that the system pressure now builds to full
operational pressure.

12
NOTES

13
BENDIX®AD-IS®AIR DRYER & RESERVOIR SYSTEM
TROUBLESHOOTING CHART
SYMPTOM CAUSE REMEDY
1. Dryer is constantly cycling
or purging.
A. Excessive system leakage. A. Test for excessive system leakage. Allowable leakage
observed at the dash gauge:
- Single vehicle - 1 psi/minute.
- Tractor/trailer - 3 psi/minute.
Using a soap solution, test the vehicle for leakage at the
fittings, drain valves and system valves and any accessories
(i.e. air suspension) connected to the Bendix®AD-IS®air dryer
auxiliary ports. If an accessory is suspected to be the cause
of leakage, disconnect that accessory from the air dryer, plug
the auxiliary port that it was in, and retest the AD-ISair dryer
for proper purge cycling. Repair or replace as necessary.
B. Defective delivery check valve. B. Build system pressure to governor cut-out. Wait one (1)
minute for the completion of the purge cycle. Using a soap
solution at the exhaust of the purge valve, leakage should
not exceed a one inch bubble in less than five (5) seconds.
If a rapid loss of pressure is found, the following procedure
will determine if the delivery check valve is malfunctioning:
Build system pressure to governor cut-out and allow a full
minute for the normal dryer purge cycle to empty the purge
reservoir. Switch off the engine and apply and release the
brakes so that the system pressure reaches governor cut-in.
The purge valve will return to its closed position. The purge
reservoir has a drain valve which is opened by moving the
center lever away from its closed position. Open the drain
valve and wait 10 seconds to allow any residual purge
pressure to be released. Release the lever, closing the drain
valve. Carefully remove the air dryer cartridge using a strap
wrench and then test for air leaking through the center of
the threaded boss by applying a soap solution to the area.
Replace the delivery check valve if there is excessive leakage
(exceeding a one inch bubble in five (5) seconds).
Grease the seal on the air dryer cartridge before reinstalling.
Be sure the drain valve on the purge reservoir is not leaking
before restoring the vehicle to service.
C. Defective governor. C. Check the governor at both the “cut-in” and “cut-out” position
for (i) proper pressures and (ii) excessive leakage at fittings
and exhaust.
D. Compressor unloader mechanism
leaking excessively.
D. Remove the air strainer, or fitting, from compressor inlet cavity.
With the compressor unloaded, check for unloader piston
leakage. Slight leakage is permissible.

14
BENDIX®AD-IS®AIR DRYER & RESERVOIR SYSTEM
TROUBLESHOOTING CHART
SYMPTOM CAUSE REMEDY
2. Water in the vehicle
reservoirs.
A. Maximum air dryer inlet temperature is
exceeded due to improper discharge
line length.
A. Check for excessive carbon build-up in the compressor
discharge line. Replace if required. Make certain that the
discharge line length is at least 6 ft. Increase the discharge line
length and/or diameter to reduce air dryer inlet temperature.
B. Air system charged from outside
air source (outside air not passing
through the air dryer).
B. If the system must have an outside air fill provision, the outside
air should pass through the air dryer.
C. Excessive air usage – Air dryer not
compatible with the vehicle air system
requirement (Improper air dryer/
vehicle application).
C. Refer to the Bendix Advanced Troubleshooting Guide for Air
Brake Compressors (BW1971) for proper application of the
Bendix®AD-IS®air dryer & reservoir system. An extended
purge model (Bendix®AD-IS® EP) is available for many higher
air usage vehicles, such as city buses and construction
vehicles.
If the vehicle is equipped with high air usage accessories,
such as trailer pump-off systems or central tire inflation, the
air for these accessories must by-pass the dryer reservoir
system.
D. Desiccant requires replacement. D. Replace the desiccant cartridge assembly.
E. Air by-passes desiccant cartridge
assembly.
E. If the vehicle uses a Holset®compressor, inspect the feedback
check valve for proper installation and operation.
F. Air dryer not purging. F. Refer to Symptom 6.
G. Purge (air exhaust) time is insufficient
due to excessive system leakage.
G. Refer to Symptom 1.
3. Safety valve on the air
dryer is “popping off” or
exhausting air.
A. Defective AD-IS air dryer & reservoir
system delivery check valve.
A. Test to determine if air is passing through the check valve.
Repair or replace. Refer to Symptom 1, Remedy B.
B. Safety valve setting too low (<150 psi) B. Replace the safety valve.
C. System pressure too high (>135 psi) C. Test with an accurate gauge. Replace the governor if
necessary.
D. Excessive pressure pulsations from
compressor. (Typical single cylinder
type).
D. Increase volume in discharge line. This can be accomplished
by adding a 90 cubic inch (or larger) reservoir between the
compressor and the AD-IS air dryer & reservoir system.
4. Constant exhaust of air at
the air dryer purge valve
exhaust or unable to build
system pressure. (Charge
mode.)
A. Air dryer purge valve leaking
excessively.
A. With the compressor loaded, apply a soap solution on the
purge valve exhaust, to test for excessive leakage. Repair or
replace the purge valve as necessary.
B. Purge valve frozen open–faulty heater
and thermostat, wiring, or blown fuse.
B. Refer to paragraph 5 of the Operation and Leakage Tests
for the heater and thermostat test.
C. Defective Bendix®AD-IS®air dryer
delivery check valve.
C. Refer to Symptom 1, Remedy B.
D. Leaking turbo cut-off valve. D. Repair or replace the purge valve assembly.
E. Defective governor. E. Check the governor at both “cut-in” and “cut-out” positions
for (i) proper pressures and (ii) excessive leakage at fittings
and exhaust.
F. Leaking purge valve control piston
seals.
F. Repair or replace the purge valve assembly.

15
BENDIX®AD-IS®AIR DRYER & RESERVOIR SYSTEM
TROUBLESHOOTING CHART
SYMPTOM CAUSE REMEDY
5. Cannot build system air
pressure.
A. Supply pressure to the air dryer is not
sufficient.
A. Ensure the supply pressure to the air dryer is greater than
110 psi after the system charges.
B. Kinked or blocked (plugged) discharge
line.
B. Check to determine if air passes through the discharge line.
Check for kinks, bends, excessive carbon deposits, or ice
blockage.
C. Excessive bends in discharge line
(water collects and freezes).
C. Discharge line should be constantly sloping from compressor
to air dryer with as few bends as possible.
D. Pressure protection valve(s) in air
dryer will not open.
D. Replace air dryer (pressure protection valves are not
serviceable).
E. Refer to Symptom 4. E. Refer to Symptom 4, Remedy A.
F. Refer to Symptom 7. F. Refer to Symptom 7, Remedies A and B.
6. Air dryer does not purge or
exhaust air.
A. Faulty air dryer purge valve. A. After determining air reaches purge valve control port by
installing a T-fitting with a pressure gauge into the governor
unloader port, repair purge valve if necessary.
B. See Causes B, E, and F for Symptom
#4.
B. Refer to Symptom 4, Remedies B, E, and F.
Also refer to Symptom 1, Remedy B.
7. Desiccant material being
expelled from the air dryer
purge valve exhaust (may
look like whitish liquid or
paste or small beads.)
A. Faulty dryer cartridge. A. Replace the Bendix®AD-IS®air dryer cartridge or AD-IS air
dryer.
B. Excessive dryer vibration. B. Check the AD-IS air dryer mounting for looseness or damage.
Repair the mounting and replace the cartridge.
8. Unsatisfactory desiccant
life.
A. Excessive system leakage. A. Refer to Symptom 1, Remedy A.
B. Wrong vehicle application for a
Bendix®AD-IS®air dryer.
B. Refer to Symptom 2, Remedy C.
C. Compressor passing excessive oil. C. Check for proper compressor installation; if the symptoms
persist, replace the compressor. Refer to Bendix Advanced
Troubleshooting Guide for Air Brake Compressor (BW1971).
9. “Pinging” noise excessive
during compressor loaded
cycle.
A. Single cylinder compressor with high
pulse cycles.
A. A slight “pinging” sound may be heard during the system build-
up when a single cylinder compressor is used. If this sound
is deemed objectionable, it can be reduced substantially by
increasing the discharge line volume.
This can be accomplished by adding a 90 cubic inch (or larger)
reservoir between the compressor and the Bendix AD-IS air
dryer & reservoir system.
10. The air dryer purge piston
cycles rapidly in the
compressor unloaded (non-
compressing) mode.
A. Compressor fails to unload. A. Check air hose from the governor to the compressor for a
missing, kinked, or restricted line. Install or repair the air hose.
Repair or replace the compressor unloader.

16
SD-08-2418 Rev. 007 © 2018 Bendix Commercial Vehicle Systems LLC, a member of the Knorr-Bremse Group • 04/18 • All Rights Reserved
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