BENDIX AD-IS - Mounting instructions

1
®
DESCRIPTION
ThefunctionofboththeBendix®AD-IS®(IntegratedSolution
Air Dryer) air dryer and reservoir system and the Bendix®
AD-IS®PuraGuard®oil coalescing air dryer and reservoir
system is to collect and remove air system contaminants
insolid, liquid andaerosol form beforethey enter thebrake
systemand to provide—asa module—heavy vehicleswith
an integrated vehicle air dryer, purge reservoir, governor
and a number of the charging valve components in a
module. These components have been designed as an
integrated air supply system.
Both air dryer and 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 necessity for daily manual draining of the reservoirs
is eliminated.
Bendix®AD-IS®and AD-IS®PuraGuard®(Oil Coalescing) Air Dryer
and Reservoir Systems
DESICCANT
CARTRIDGE
(PURAGUARD®
OILCOALESCING
SHOWN)
PURGE
RESERVOIR
24
AUX1
AUXILIARY
DELIVERY PORTS
(4)
GOVERNOR
PRESSURE
PROTECTION
VALVES (4)
HEATER /
THERMOSTAT
SAFETY VALVE
AIR DRYER
PART NUMBER
STAMPED HERE
MOUNTING
BOLTS (3)
22
SEC
DELIVERYTO
SECONDARY
RESERVOIR
21
PRI
DELIVERY TO PRIMARY
RESERVOIR PRESSURE PROTECTION
VALVES (4)
SD-08-2418
MOUNTING
HOLES (4)
TABLE 1 - PORT DESIGNATIONS
1
IN
SUPPLY FROM
COMPRESSOR
UNL
GOVERNOR
UNLOADER (2)
PURGE VALVE
RES
GOVERNOR
RESERVOIR (2)
EXH
GOVERNOR
EXHAUST
23
AUX2
AUXILIARY
DELIVERY
PORT
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 ControlAir (D-2A™Governor) 2
RES Common Reservoir Pressure (D-2A™Governor) 2
EXH Governor Exhaust 1
FIGURE 1 - BENDIX® AD-IS®AND AD-IS®PURAGUARD®OIL COALESCING AIR DRYER AND RESERVOIR SYSTEMS
DESICCANT
CARTRIDGE
(STANDARD SHOWN)

2
FIGURE 2 - BENDIX® AD-IS®AIR DRYER AND RESERVOIR SYSTEM CHARGE CYCLE
The Bendix®AD-IS®PuraGuard®oil coalescing air dryer
has an identical appearance to the standard AD-IS®air
dryer, but contains a coalescing media at the inlet of the
desiccant bed. 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 standardAD-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
PuraGuardoilcoalescing air dryersorcartridges, however,
PuraGuardoil coalescing airdryersor cartridges mustonly
be serviced with like replacements.
Note: Unless otherwise stated in this manual, AD-IS air
dryerandreservoirsystems refers to boththestandardand
PuraGuardoil coalescing air dryer and reservoir systems.
The function of the pressure protection valves is to protect
eachreservoirfrom a pressurelossinthe other reservoiror
a pressure loss in an air accessory. Each of the pressure
protection valves in the AD-IS air dryer and reservoir
systems may have different pressure settings. These are
factory set and must not be changed or adjusted.
The air dryer and reservoir system consists of a “spin on”
desiccant cartridge secured to a base assembly. The
base assembly contains a delivery check valve assembly,
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
(TOACCESSORIES)
SEE
NOTE 1
Note 1:
The Bendix®AD-IS® air dryer and reservoir system
purgepiston hasa purge controlchannel drain.This
allows any condensation in this area to flow past a
diaphragm in the top of the purge piston and out
througha channel in the middle of the central bolt of
the purge assembly to be drained. During the purge
cycle this drain is closed.
SAFETY
VALVE PURGE
RESERVOIR
DRAIN VALVE
SECONDARY
RESERVOIR
SECONDARY
PORT (SEC)
PURGE
RESERVOIR
PURGE
ORIFICE
OILCOALESCING FILTER
(BENDIX®AD-IS®PURAGUARD®
OILCOALESCINGAIR DRYER)
AD
C
B
PURGE
CONTROL
CHANNEL
DIAGRAM SHOWS ALL PRESSURE
PROTECTION VALVES OPEN.

3
BENDIX®AD-IS®AIR DRYER AND RESERVOIR
SYSTEM OPERATION: GENERAL
(Refer to Figure 2.)
TheAD-IS air dryer and 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,secondaryreservoirandaccessories, and control
the compressor/dryer charge cycle.
FIGURE 3 - BENDIX® AD-IS®AIR DRYER AND RESERVOIR SYSTEM PURGE CYCLE
safety valve, heater and thermostat assembly, pressure
protection valves, threaded air connections and the purge
valve assembly.
The removable purge valve assembly incorporates the
purgevalve mechanism and a turbochargercut-offfeature
that is designed to prevent loss of engine “turbo” boost
pressure during the purge cycle of the Bendix® AD-IS®air
dryer and reservoir system. For ease of maintenance, all
replaceable assemblies can be serviced without removal
of the air dryer and reservoir system from its mounting on
the vehicle. Refer to Preventive Maintenance section.
DIAGRAM SHOWS ALL PRESSURE
PROTECTION VALVES OPEN.
COMPRESSOR
GOVERNOR
DESICCANT
BED
DELIVERY
CHECK VALVE
(CLOSED)
PRIMARY
PORT (PRI)
PURGE VALVE
(OPEN)
TURBO
CUT-OFF
VALVE
(CLOSED)
ENGINE
TURBO
UNLOADER
PORT
SUPPLY
PORT
PRIMARY
RESERVOIR
PRESSURE
PROTECTION
VALVES
AUXILIARY PORTS
(TOACCESSORIES)
EXHAUST
SAFETY
VALVE PURGE
RESERVOIR
DRAIN VALVE
SECONDARY
RESERVOIR
SECONDARY
PORT (SEC)
PURGE
RESERVOIR
PURGE
ORIFICE
OILCOALESCING FILTER
(BENDIX®AD-IS®PURAGUARD®
OILCOALESCINGAIR DRYER)
AD
C
B
PURGE
CONTROL
CHANNEL

4
AIR DRYER AND RESERVOIR SYSTEM
OPERATION: GENERAL
The Bendix®AD-IS®air dryer and reservoir system
alternatesbetweentwomodesor “cycles” during operation:
the Charge Cycle and the Purge Cycle. The following
describes these “cycles” of operation.
CHARGE CYCLE (Refer to Figure 2.)
Whenthecompressor is runningloaded (compressing air),
compressed air flows 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 flows into the desiccant cartridge,
whereit flows throughanoil separator—or coalescingfilter
if equipped with a PuraGuard®oil coalescing cartridge—
which removes water in liquid form as well as liquid oil and
solid contaminants.
Air then flows into the desiccant drying bed and becomes
progressively more dry 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 flows to the delivery check valve
and through an orifice 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 fills, 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
suppliedto the primary reservoir, secondaryreservoir, and
accessories. If the pressure protection valves are preset
to different values the valves will open—in order of lowest
setting to highest setting—when charging a flat 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.)
Whenairbrakesystempressurereachesthecut-outsetting
of the governor, the governor unloads the compressor
activating the purge cycle of the air dryer and reservoir.
The governor unloads the compressor by allowing air
pressure to fill the line leading to the compressor unloader
mechanism. Thissuspends the deliveryofcompressed air
to the AD-IS®air dryer and reservoir system.
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
(coveredin theTurboCut-offFeature sectionof this piece).
Water and contaminants captured are expelled immediately
when the purge valve opens. In addition, air—which
was flowing through the desiccant cartridge—changes
direction and begins to flow toward the open purge valve.
Contaminants collected by the air dryer are removed by
air flowing 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.
Theactual regeneration ofthedesiccant drying bedbegins
as dry air from the purge reservoir flows through the purge
orifice into the desiccant bed. Pressurized air from the
purge reservoir expands after passing through the purge
orifice; its pressure lowers and its volume increases. The
flow of dry air through the drying bed regenerates the
desiccant material by removing any water vapor adhering
toit. Approximately 30 seconds are required for the entire
contents of the purge reservoir of an AD-IS air dryer and
reservoirsystem to flow 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. After the purge cycle is complete, the air
dryer and reservoir system is ready for the next charge
cycle to begin.
TURBO CUT-OFF FEATURE (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-ISair 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 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.

5
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. Experienceisavaluableguideindeterminingthe best
maintenance interval for any one particular operation.
Every 900 operating hours, or 25,000 miles, or three
(3) months:
1. Check for moisture in the air brake system by opening
reservoir drain valves and checking for the presence
ofwater. If moistureis 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.
Thismaybe due toaccessory air demandsorsome
unusual air requirement that does not allow the
compressor to load and unload (compressing and
non-compressingcycle) in anormal 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, todetermineifanychanges
arenecessary. Specification BW-100-Aisavailable
from the Bendix TechTeam at 1-800-247-2725 or
www.bendix.com.
C. The location of the air dryer and reservoir system
is too close to the air compressor. Refer to Bendix
Specification BW-110-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.
For Bendix®AD-IS®PuraGuard®oil coalescing
air dryers only - every 3,600 operating hours, or
100,000 miles, or 12 months:
Oil removal requirements for air brake quality vary
by vehicle manufacturer. Because vehicle vocation
and maintenance can influence when the Bendix®
AD-IS®PuraGuard®oil coalescing air dryer cartridge
requires replacement, each fleet should modify their
replacement schedule based on experience. The
change out interval will be extended if the compressor
passes a low level of particles. The interval will be
reduced if excessive carbon particles are delivered to
the dryer inlet. Higher compressor build up times at
idle, as well as water or oil in downstream reservoirs
indicate an AD-IS PuraGuard oil coalescing air dryer
desiccant cartridge may need to be replaced.
Note:Asmall 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
also normal.
2. Visuallycheck forphysical damage, such as chaffedor
broken air and electrical lines, and broken or missing
parts.
3. ChecktheAD-IS®airdryerandpurge reservoir boltsfor
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.
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 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 may void the warranty.
FIGURE 4 - HEATER AND THERMOSTAT CONNECTOR
HEATER & THERMOSTAT
CONNECTOR

6
OPERATION & LEAKAGE TESTS (REFER TO THE
TROUBLESHOOTING CHART IN THIS MANUAL)
For additional information see video BW2237.
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
thattheBendix®AD-IS®air dryer purges withanaudible
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
thepurgevalvewiththecompressorinthechargemode
(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 theAD-IS air dryer purges with an audible burst of
air,followed immediately byapproximately 30seconds
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
pressureand is followedby a purge.If the systemdoes
not follow this pattern, refer to Symptoms 5 and 6 in
the Troubleshooting Chart .
5. Check the operation of the end cover heater and
thermostatassembly 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
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
blownfuse, broken wires,or corrosionin 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
andheaterassemblytobelow40°Fahrenheit. Using
an ohmmeter, check the resistance between the
electrical pins in the air dryer and reservoir system
connector half. The resistance should be 1.5 to 3.0
ohmsfor the12 volt heater assembly,and 6.0to 9.0
ohms for the 24 volt heater assembly.
Warm the thermostat and heater assembly to
approximately 90° Fahrenheit and again check the
resistance. The resistance should exceed 1000
ohms. If the resistance values obtained are within
thestatedlimits,thethermostatandheaterassembly
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. Theprimary or secondarygauge should riseuntil
it reaches approximately 106 psi (±6 psi), then level
off (or a momentary slight fall) as the next pressure
protectionvalve opens—supplying its reservoir. When
thatpressuregaugepasses through approximately 106
FIGURE 5 - PRESSURE PROTECTION VALVE LOCATIONS
PRESSURE
PROTECTION
VALVE
LOCATIONS
THE BENDIX®AD-IS®
AIR DRYER GOVERNORSARE
NON-ADJUSTABLE
AND FEATURESABREATHER
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.

7
psi(±6psi) thereshouldbe anassociatedlevelingoff(or
momentaryslightfall)ofpressure as the third andfourth
pressureprotection valves open.Then theprimary and
secondary gauges should increase together until they
reach their full pressure of approximately 130 psi (±5
psi).
IftheBendix®AD-IS®airdryerandreservoirsystemdoes
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 and reservoir system.
NOTE: There are no kits available for the servicing
of the pressure protection valves. Warning: Do not
attempt to adjust or service the pressure protection
valves—incorrect pressure protection valve settings
canresult in automatic application ofthe 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
andreservoir,useonlygenuineBendix®brand replacement
parts. For ease in servicing, the AD-IS air dryer and
reservoirhavebeen designed sothatmaintenancekits can
be installed without removing the air dryer and reservoir
from the vehicle. CAUTION: 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—ithasbeendeterminedthatoneormorecomponents
ofthe air dryerrequires replacement ormaintenance, refer
to the Maintenance Kit listing shown in this manual or the
Bendix®QuickReferenceCatalog for the appropriatekit(s).
The Quick Reference catalog (BW1114) can be ordered
and viewed on line at www.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
AND 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
thattheBendix®AD-IS®airdryerpurges(withanaudible
burstof air),followed immediately byapproximately 30
seconds of air flowing out of the purge valve.
3. “Fan”the service brakes to reducesystem 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. Itis recommended thatthetotalair system betestedfor
leakageto assure thattheAD-ISair dryerand reservoir
system will not cycle excessively.
BRAKING SYSTEM PROTECTION
TheAD-IS air dryer allows the system to maintain one brake
circuit up to about 100 psi even after a pressure loss in the
otherbrakecircuit. This allows a vehicletobemoved (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
ofreducedbrakingcapacity applications beforetheparking
brakes automatically apply and stay on.
See Bendix publication BW5057 "Air Brake Handbook."
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) 5006698
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

8
FIGURE 7 - SPLASH SHIELD BRACKET AND COVER - (EXPLODED VIEW)
SPLASH SHIELD
BRACKET
SPLASH SHIELD
COVER
LOCK TABS

9
FIGURE 6 - BENDIX® AD-IS®AIR DRYER AND RESERVOIR SYSTEM DELIVERY CHECK VALVE
GOVERNOR GASKET
(SPECIALGASKET,
SEEASSEMBLY NOTE 6) GOVERNOR
(NON-ADJUSTABLE,
130 PSI CUT-OUT)
BOLTS
ADAPTER
LARGE
O-RING
SPRING
CHECK VALVE
BODY
SMALL
O-RING
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 AND RESERVOIR
SYSTEM BYPASS
Totemporarilybypasstheairdryer,followtheseprocedures:
Adhere to the General Safety Guidelines outlined
elsewhere in this document.
Makesurethatallresidual pressure has been releasedand
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-ISairdryer(see Figure 1forlocation). Notethat a short
puffof trapped airmayvent from thesafetyvalve port when
removing the valve. Install a T-fitting into the port. Using
anyadapters necessary, reinstall thesafety valve inone of
thebranchesoftheT-fitting. Usingany adapters necessary,
install the air supply line into the remaining T-fitting port.
After testing the T-fitting 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 and reservoir system, the
system pressure still does not build, use the following
procedure to remove, clean, and reinstall the delivery
check valve.

10
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.
De-pressurize the air brake system following the general
safety precautions outlined elsewhere in this document.
Also, always de-pressurize the air dryer purge reservoir
before servicing the air dryer.
This procedure does not require removal of the Bendix®
AD-IS®air dryer and reservoir from the vehicle.
1. Remove the line from the governor and mark for easy
re-installation.
2. Remove the bolts attaching the governor to the
AD-IS air dryer and reservoir system and retain for
re-assembly.
3. Removethe governor fromthe air dryer. Beaware that
ashortpuffoftrappedairmayvent when the governor is
removed.Retainthe governor gasketforre-assembly 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.
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 and 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 delivery check valve from seating),
replace the AD-IS air dryer.
4. Inspectthedeliverycheckvalve,o-rings, etc. for wear or
damage. Replace, if necessary, using the check valve
replacementkitavailableatanyauthorizedBendixparts
outlets.
5. Inspect all air line fittings 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-ringonthe check valvebodyby 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
installedoverthe set offourstraightguide 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
in the delivery port so that the o-ring rests on its seat
and the free end of the spring is visible.
5. Greasethe adapter andtheremaininglarger o-ring and
install it onto the fitting.
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 line to the governor.
8. Before placing vehicle back into service, check to see
that the system pressure now builds to full operational
pressure.

11
BENDIX®AD-IS®AIR DRYER AND 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 dash gauge:
- Single vehicle - 1 psi/minute.
- Tractor trailer - 3 psi/minute.
Using soap solution, test vehicle for leakage at fittings,
drain valves and system valves and any accessories (i.e.
air suspension) connected to the Bendix®AD-IS®air dryer
auxiliaryports. Ifanaccessoryissuspectedtobethecause
ofleakage,disconnectthataccessoryfromtheairdryer,plug
theauxiliaryportthatitwasin,andretesttheAD-ISairdryer
for proper purge cycling. Repair or replace as necessary.
B. Defective delivery check valve. B. Buildsystem pressuretogovernorcut-out.Wait1minute for
completionofpurgecycle.Usingsoapsolutionatexhaustof
purge valve, leakage should not exceed a 1" bubble in less
than 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 “fan” 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.
Carefullyremovetheairdryercartridgeusingastrapwrench
andthentestforairleakingthroughthecenterofthethreaded
boss by applying a soap solution to the area. Replace the
deliverycheckvalveifthereisexcessiveleakage(exceeding
a 1" bubble in 5 seconds).
Re-grease the seal on the air dryer cartridge before
reinstalling. Be sure the drain valve on the purge reservoir
is not leaking before restoring vehicle to service.
C. Defective governor. C. Check governor at both “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 air strainer, or fitting, from compressor inlet cavity. With compressor unloaded, check for unloader piston
leakage. Slight leakage is permissible.

12
BENDIX®AD-IS®AIR DRYER AND RESERVOIR SYSTEM
TROUBLESHOOTING CHART
SYMPTOM CAUSE REMEDY
2. Water in vehicle reservoirs A. Maximumairdryerinlettemperatureis
exceeded due to improper discharge
line length.
A. Checkforexcessivecarbonbuildupincompressordischarge
line. Replace if required. Make certain that discharge line
length is at least 6 ft. Increase 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 air dryer).
B. Ifsystemmusthaveoutsideairfillprovision,outsideairshould
pass through air dryer.
C. Excessive air usage - Air dryer not
compatible with vehicle air system
requirement (Improper air dryer/
vehicle application)
C. Refer to Bendix Advanced Troubleshooting Guide for Air
Brake Compressors (BW1971) for proper application of the
Bendix®AD-IS®airdryerandreservoirsystem. Anextended
purgemodel(Bendix®AD-IS®EP)isavailableformanyhigher
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 desiccant cartridge assembly.
E. Air by-passes desiccant cartridge
assembly. E. If vehicle uses Holset compressor, inspect feedback check
valve for proper installation and operation.
F. Air dryer not purging. F. Refer to Symptom 6.
G. Purge (air exhaust) time insufficient
due to excessive system leakage. G. Refer to Symptom 1.
3. Safety valve on air dryer
“popping off” or exhausting
air.
A. DefectiveAD-ISairdryerandreservoir
system delivery check valve. A. Testtodetermineifairispassingthroughcheckvalve.Repair or replace. Refer to Symptom 1, Remedy B.
B. Safetyvalvesettingtoolow(<150p.s.i.) B. Replace safety valve.
C. Systempressuretoohigh(>135p.s.i.) C. Test with accurate gauge. Replace governor if necessary.
D. Excessive pressure pulsations from
compressor. (Typical single cylinder
type).
D. Increasevolumeindischargeline.Thiscanbeaccomplished
by adding a 90 cubic inch (or larger) reservoir between the
compressor and theAD-IS®air dryer and reservoir system.
4. Constantexhaustofairatair
dryer purge valve exhaust
or unable to build system
pressure. (Charge mode.)
A. Air dryer purge valve leaking
excessively. A. Withcompressorloaded,applysoapsolutiononpurgevalve exhaust, to test for excessive leakage. Repair or replace
purge valve as necessary.
Refer to Technical Bulletin TCH-008-040.
B. Purgevalvefrozenopen-faultyheater
and thermostat, wiring, blown fuse. B. Refertoparagraph5oftheOperationandLeakageTestsfor heater and thermostat test.
C. Defective AD-IS air dryer delivery
check valve. C. Refer to Symptom 1, Remedy B.
D. Leaking Turbo Cut-Off valve. D. Repair or replace purge valve assembly.
E. Defective governor. E. Check governor at both “cut-in” and “cut-out” position for (i)
proper pressures and (ii) excessive leakage at fittings and
exhaust.
F. Leaking purge valve control piston
seals. F. Repair or replace purge valve assembly.

13
BENDIX®AD-IS®AIR DRYER AND RESERVOIR SYSTEM
TROUBLESHOOTING CHART
SYMPTOM CAUSE REMEDY
5. Cannot build system air
pressure. A. Supplypressuretotheairdryerisnot sufficient. A. Ensure the supply pressure to the air dryer is greater than 110 psi after the system charges.
B. Kinkedorblocked(plugged)discharge
line. B. Check to determine if air passes through discharge line. Check for kinks, bends, excessive carbon deposits, or ice
blockage.
C. Excessive bends in discharge line
(water collects and freezes). C. Dischargelineshouldbeconstantlyslopingfromcompressor 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, RemedyA.
F. Refer to Symptom 7. F. Refer to Symptom 7, RemediesAand 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. SeeCausesB,E,andFforSymptom
#4. B. Refer to Symptom 4, Remedies B, E, and F. Also refer to Symptom 1, Remedy B.
7. Desiccant material being
expelledfromairdryerpurge
valveexhaust(maylook like
whitish liquid or paste or
small beads.)
A. Faulty dryer cartridge. A. Replace the Bendix®AD-IS®air dryer cartridge orAD-IS air
dryer.
B. Excessive dryer vibration. B. ChecktheAD-ISairdryermountingforloosenessordamage.
Repair mounting and replace cartridge.
8. Unsatisfactorydesiccantlife. A. Excessive system leakage. A. Refer to Symptom 1, RemedyA.
B. Wrong vehicle application for AD-IS®
air dryer. B. Refer to Symptom 2, Remedy C.
C. Compressor passing excessive oil. C. Check for proper compressor installation; if symptoms
persist, replace compressor. Refer to Bendix Advanced
TroubleshootingGuideforAirBrakeCompressor(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 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 theAD-ISair
dryer and 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 governor to compressor for a missing,
kinked or restricted line. Install or repair air hose.
Repair or replace compressor unloader.

14
BW2234 © 2011 Bendix Commercial Vehicle Systems LLC, a member of the Knorr-Bremse Group • 07/11 • All Rights Reserved