BENDIX AD-IS - User manual

1
®
DESCRIPTION
The function of the Integrated Solution Air Dryer (AD-IS®)
and Reservoir System is to provide heavy vehicles with an
integratedvehicleairdryer,purgereservoir,governoranda
number of the charging valve components in a module.
These have been designed as an integrated air supply
system.
The AD-IS®air dryer and reservoir system collects and
removes air system contaminants in solid, liquid and vapor
form before they enter the brake system. It provides 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
reservoirsiseliminated.
FIGURE 1 - AD-IS®AIR DRYER AND RESERVOIR SYSTEM
Bendix®AD-IS®Air Dryer and Reservoir System
DESICCANT
CARTRIDGE
PURGE
RESERVOIR
24
AUX1
AUXILIARY
DELIVERYPORTS
(4)
GOVERNOR
PRESSURE
PROTECTION
VALVES(4)
HEATER /
THERMOSTAT
SAFETY VALVE
AD-IS®AIRDRYER
PART NUMBER
STAMPEDHERE
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
Air
Connection Function/Connection QTY
Port ID
1
IN
21
PRI
22
SEC
24
AUX1
23
AUX2
UNL Unloader Control Air (D-2A™Governor) 2
RES CommonReservoirPressure
(D-2A™Governor) 2
EXH Governor Exhaust 1
TABLE 1 - PORT DESIGNATIONS
InletPort(airin). 1
Delivery Port out (to Primary reservoir) 1
Delivery Port out (to Secondary reservoir) 1
Auxiliary Delivery Port (air out). 4
Auxiliary Delivery Port (air out). 1
1
IN
SUPPLY FROM
COMPRESSOR
UNL
GOVERNOR
UNLOADER (2)
PURGE VALVE
RES
GOVERNOR
RESERVOIR (2)
EXH
GOVERNOR
EXHAUST
23
AUX2
AUXILIARY
DELIVERY PORTS
(2)

2
FIGURE 2 - AD-IS®AIR DRYER AND RESERVOIR SYSTEM CHARGE CYCLE
COMPRESSOR
GOVERNOR
PURGE
CONTROL
CHANNEL
DESICCANT
BED
DELIVERY
CHECK
VALVE
(OPEN) PURGE RESERVOIR
PRIMARY
PORT
(PRI)
PURGE
VALVE
(CLOSED)
TURBO CUT-
OFF VALVE
(OPEN)
ENGINE
TURBO
UNLOADER
PORT
INLET
PORT
(IN)
OIL
SEPARATOR
PURGE
ORIFICE
PRIMARY
RESERVOIR
PRESSURE PROTECTION
VALVES
AUXILIARY PORTS
(TO ACCESSORIES)
SEE
NOTE 1
Note 1:
The AD-IS® air dryer and reservoir system
purge piston has a purge control channel
drain. This allows any condensation in this
area to flow past a diaphragm in the top of the
purge piston and out through a 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
The function of the pressure protection valves is to protect
eachreservoirfromapressurelossin the other reservoir or
a pressure loss in an air accessory. Each of the pressure
protectionvalvesintheAD-IS®airdryerandreservoirsystem
mayhave different pressure settings,but these are factory
set and must not be changed or adjusted.
The air dryer and reservoir system consists of a “spin on”
desiccantcartridgesecured to a base assembly. The base
assemblycontainsadeliverycheck valve assembly,safety
valve,heaterandthermostatassembly,pressureprotection
valves, threaded air connections and the purge valve
assembly.
Theremovablepurgevalveassemblyincorporates thepurge
valvemechanism and a turbochargercut-offfeature that is
designed to prevent loss of engine “turbo” boost pressure
duringthe purge cycle oftheAD-IS®air dryerandreservoir
system. For ease of maintenance, all replaceable
assembliescanbeservicedwithoutremovaloftheairdryer
andreservoirsystemfromitsmountingonthevehicle. Refer
to PreventiveMaintenancesection.
A
D
C
B
SECONDARY
RESERVOIR
SECONDARY
PORT
(SEC)
DIAGRAMSHOWSPRESSURE
PROTECTIONVALVESA&B OPEN,
C& DCLOSED.

3
FIGURE 3 - AD-IS®AIR DRYER AND RESERVOIR SYSTEM PURGE CYCLE
COMPRESSOR
GOVERNOR
PURGE
CONTROL
CHANNEL
DESICCANT
BED
DELIVERY
CHECK
VALVE
(CLOSED) PURGE
RESERVOIR
PURGE
VALVE
(OPEN)
TURBO CUT-
OFF VALVE
(CLOSED)
ENGINE
TURBO
OIL
SEPARATOR
PURGE
ORIFICE
PRIMARY
RESERVOIR
GOVERNOR SIGNALS AIR
COMPRESSOR TO SUSPEND
COMPRESSED AIR SUPPLY
TO AD-IS®AIR DRYER
EXHAUST
PRIMARY
PORT
(PRI)
UNLOADER
PORT
INLET
PORT
(IN)
SAFETY
VALVE AUXILIARY PORTS
(TO ACCESSORIES) PURGE
RESERVOIR
DRAIN VALVE
AD-IS®AIR DRYER AND RESERVOIR SYSTEM
OPERATION: GENERAL (Refer to Figure 2)
The AD-IS®air dryer and reservoir system is designed to
receive compressed air from the vehicle air compressor,
clean and dry the air, deliver air to the vehicle’s primary
reservoir,secondaryreservoirandaccessories,andcontrol
the compressor/dryer charge cycle.
AIR DRYER AND RESERVOIR SYSTEM
OPERATION: GENERAL
TheAD-IS®airdryerandreservoirsystemalternatesbetween
two operational modes or “cycles” during operation: the
Charge Cycle and the Purge Cycle. The following
descriptionsareseparated into these “cycles” of operation.
CHARGE CYCLE (Refer to Figure 2)
When the compressor is loaded (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,
oilvapor,waterandwatervapor.
Traveling through the discharge line and into the air dryer,
thetemperatureof the compressed air falls, causingsome
PRESSURE PROTECTION
VALVES
A
D
CB
SECONDARY
RESERVOIR
SECONDARY
PORT
(SEC)
DIAGRAMSHOWSALLPRESSUREPROTECTIONVALVES
OPEN.

4
ofthe contaminants to condenseand drop to thebottom of
the air dryer and reservoir system purge valve assembly,
ready to be expelled at the next purge cycle. The air then
flowsintothedesiccantcartridge,where it flows through an
oilseparatorwhichremovesliquidoilandsolidcontaminants.
Air then flows into the desiccant drying bed and becomes
progressivelydrieraswatervaporadherestothedesiccant
material in a process known as “ADSORPTION.”
Dry air exits the desiccant cartridge through the center of
thebaseassembly. The air then flows to thedeliverycheck
valve and also through an orifice into the purge reservoir.
Thedeliverycheckvalveopens,supplyingairtothepressure
protectionvalves(A)through(D)simultaneously,thesafety
valve,andalsoto thereservoirportofthe attachedgovernor.
The purge reservoir fills, storing air that will be used to
reactivate the desiccant during the purge cycle. This air is
available to supply downstream components during the
chargemode.
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
accessories. Ifthepressureprotectionvalvesare preset to
differentvaluesthevalveswill openinorderoflowestsetting
to highest setting when charging a flat system.
Theairdryerandreservoirsystemwill remain in the charge
cycle until the air brake system pressure builds to the
governor cut-out setting of approximately 130 p.s.i.
PURGE CYCLE (Refer to Figure 3.)
Whenairbrakesystempressurereachesthe cut-out setting
ofthe governor, the governorunloadsthe compressor and
thepurgecycleoftheairdryerandreservoir system begins.
The governor unloads the compressor by allowing air
pressure to fill the line leading to the compressor unloader
mechanism - causing the delivery of compressed air to
theAD-IS®airdryerandreservoirsystem to be suspended.
Similarly, the governor also supplies air pressure to the
AD-IS®airdryerand reservoirsystempurgecontrolchannel.
The AD-IS®air dryer and reservoir system purge piston
moves down in response to this air pressure, causing the
purgevalvetoopentotheatmosphereandtheturbocut-off
valvetocloseoffthesupplyofairfromthe compressor (this
will be further discussed in the Turbo Cut-off Feature
section). Waterand contaminants whichhave collected in
the purge valve base are expelled immediately when the
purgevalveopens. Also,air which was flowing through the
desiccant cartridge changes direction and begins to flow
toward the open purge valve. Oil and solid contaminants
collected by the oil separator are removed by air flowing
from the purge reservoir through the desiccant drying bed
totheopenpurgevalve.
The initial purge and desiccant cartridge decompression
lasts only a few seconds and is evidenced by an audible
burst of air at the AD-IS®air dryer and reservoir system
exhaust.
The actual reactivation of the desiccant drying bed begins
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 is lowered and its volume increased.
The flow of dry air through the drying bed reactivates the
desiccantmaterialbyremovingthewatervaporadheringto
it. Approximately 30 seconds are required for the entire
contentsofthe purgereservoirofastandardAD-IS®airdryer
and reservoir system to flow through the desiccant drying
bed.
Thedeliverycheckvalveassemblypreventsairpressurein
thebrakesystemfromreturningtotheairdryerandreservoir
system 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.)
Theprimary function ofthe turbo cut-offvalve is to prevent
loss of engine turbocharger air pressure through the
AD-IS®air dryer and reservoir system when the dryer is in
theunloadedmode.
At the onset of the purge cycle, the downward travel of the
purgepistonisstoppedwhentheturbocut-off valve(tapered
portion of purge piston) contacts its mating metal seat in
thepurgevalvehousing. Withtheturbocut-off valve seated
(closed position), air in the compressor discharge line and
AD-IS®air dryerandreservoirsysteminletportcannotenter
theairdryerand reservoir system. In this manner 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
warrantymaybevoidedifintrusivemaintenanceisperformed
duringthisperiod. Purgevalvemaintenanceis permissible
duringthewarrantyperiodonlywhen usingagenuineBendix
purgevalvekit.
Becausenotwovehiclesoperate underidenticalconditions,
maintenance and maintenance intervals will vary.
Experience is a valuable guide in determining the best
maintenanceintervalfor any one particularoperation.
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 presence of
water. If moisture is present, the desiccant cartridge

5
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 exceptionallyhighand not normal fora
highwayvehicle.
Thismaybeduetoaccessoryairdemandsorsome
unusual air requirement that does not allow the
compressor to load and unload (compressing and
non-compressingcycle)inanormal 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,AppendixDtodetermineifanychanges
arenecessary.
C. Locationoftheairdryer and reservoir system istoo
close to the air compressor. Refer to Bendix
Specification BW-100-A,Appendix B for discharge
linelengths.
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
desiccantcartridge. Someoilat thedryerexhaustisnormal.
2. Visually check for physical damage such as chaffed or
broken air and electrical lines and broken or missing
parts.
3. ChecktheAD-IS®airdryerandpurgereservoirboltsfor
tightness. See Figure 1. Re-torque the three air dryer
boltsto360-420inchpoundsandthefourpurgereservoir
boltsto 300-360 inch pounds.
4. Perform the Operation & Leakage Tests listed in this
publication.
WARNING!
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
upstreamoftheair dryer and reservoirsystem. Alcohol
is removed by the dryer, but reduces the effectiveness
ofthedevice todryair. Use oftheseor othersubstances
can damage the air dryer and reservoir system 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 and reservoir system for leakage and integrity.
Repairanyleaksfound.
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. Ifpressuredropexceeds,forasinglevehicle-1
psi/minutefromeitherservicereservoir;orfortractortrailer
- 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
thepurgevalvewiththecompressor in the loadedmode
(compressing air). Apply a soap solution to the purge
valve exhaust port and observe that leakage does not
exceeda1"bubblein1second. Iftheleakageexceeds
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
approximately30secondsofairflowingoutofthe purge
valve. "Fan" the service brakes to reduce system air
pressuretogovernor cut-in. Note that the systemonce
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
follows:
FIGURE 4 - AD-IS®AIR DRYER AND RESERVOIR SYSTEM
HEATER AND THERMOSTAT CONNECTOR
HEATER & THERMOSTAT
CONNECTOR

6
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
reservoirsystemandplacethetestleadsoneachof
the connections of the female connector on the
vehicle power lead. If there is no voltage, look for a
blownfuse,brokenwires,orcorrosioninthevehicle
wiring harness. Check to see if a good ground path
exists.
B. ThermostatandHeaterOperation
Note: These tests are not possible except in cold
weatheroperation.
Turn off the ignition switch and cool the thermostat and
heaterassemblytobelow40degreesFahrenheit. 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
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
operatingproperly. Iftheresistancevaluesobtained 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 secondary gaugeshouldrise until
itreachesapproximately106 p.s.i. (±6 p.s.i.), then level
off (or a momentary slight fall) as the next pressure
protection valve opens supplying its reservoir. When
thatpressuregaugepassesthroughapproximately106
p.s.i. (±6 p.s.i.) there should be an associated leveling
off(ormomentaryslightfall)ofpressureasthethirdand
fourthpressureprotectionvalvesopen.Thentheprimary
and secondary gauges should increase together until
they reach their full pressure of approximately 130 psi
(±5 psi).
If the AD-IS®air dryer and reservoir system does not
performwithinthepressurerangesasdescribedabove,
recheck using gauges known to be accurate. If the
readings remain outside of the ranges outlined above,
replacethe AD-IS®airdryerandreservoirsystem.NOTE:
There are no kits available for the servicing of the
pressureprotectionvalves. WARNING:Do not attempt
to adjust or service the pressure protection valves -
incorrect pressure protection valve settings can
result in automatic application of the vehicle spring
brakes without prior warning in the event one of
thesupplycircuitsexperiencesrapidpressureloss.
REBUILDING THE AD-IS®AIR DRYER AND
RESERVOIR SYSTEM
GENERAL SAFETY GUIDELINES
WARNING! PLEASE READ AND FOLLOW
THESE INSTRUCTIONS TO AVOID
PERSONAL INJURYOR DEATH:
When working on or around a vehicle, the following
general precautions should be observed at all times.
1. Park the vehicle on a level surface, apply the
parking brakes, and always block the wheels.
Always wear safety glasses.
2. Stop the engine and remove 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 beinoperation, EXTREME CAUTION should
be used to prevent personal injury resulting from
contact with moving, rotating, leaking, heated or
electrically charged components.
FIGURE 5 - PRESSURE PROTECTION VALVE LOCATIONS
PRESSURE
PROTECTION
VALVE
LOCATIONS
AD-IS
®
AIR DRYER
GOVERNORS
ARE NON-
ADJUSTABLE
AND FEATURE A
BREATHERVALVE
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
be designed specifically for such applications and
systems.
9. Components with stripped threads or damaged
parts should be replaced rather than repaired. Do
not attempt repairs requiring machining or welding
unless specifically stated and approved by the
vehicle and component manufacturer.
10. Prior to returning the vehicle to service, make
certain all components and systems are restored
to their proper operating condition.
11. For vehicles with Antilock 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.
GENERAL
When rebuilding or replacing components of the air dryer
and reservoir system use only genuine Bendix parts. For
easeinservicing,theAD-IS®airdryerandreservoirsystem
hasbeendesignedsothatany ofthefollowingmaintenance
kits can be installed without removing the air dryer and
reservoir system from the vehicle. CAUTION: Always
depressurize the air dryer and reservoir system purge
reservoir, and all other reservoirs on the vehicle to 0 p.s.i.
beforeservicing the air dryerand reservoir system.
3. Do not attempt to install, remove, disassemble or
assemble a component until you have read and
thoroughly understand the recommended
procedures. Useonlythepropertoolsandobserve
all precautions pertaining to use of those tools.
4. 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 an
AD-IS®air dryer system or a dryer reservoir
module, be sure to drain the purge reservoir.
5. Following the vehicle manufacturer’s
recommended procedures, deactivate the
electrical system in a manner that safely removes
all electrical power from the vehicle.
6. Never exceed manufacturer’s recommended
pressures.
7. Never connect or disconnect a hose or line
containing pressure; it may whip. Never remove a
component or plug unless you are certain all
system pressure has been depleted.
8. Use only genuine Bendix®replacement parts,
components and kits. Replacement hardware,
tubing, hose, fittings, etc. must be of equivalent
size, type and strength as original equipment and
FIGURE 6 - SPLASH SHIELD BRACKET AND COVER - (EXPLODED VIEW)
SPLASH
SHIELD
BRACKET
SPLASH
SHIELD
COVER
LOCK TABS

8
If,aftercompletingthe routine operation and leakage tests,
ithasbeendeterminedthatoneormorecomponentsof the
air dryer and reservoir system requires replacement or
maintenance,refertothe followinglisttofindtheappropriate
kit(s).
MAINTENANCE KITS AVAILABLE:
•Service New Desiccant Cartridge Kit - Part Number
5008414: Thiskitcontainsthepartsnecessarytochange
the desiccant cartridge only.
•DeliveryCheckValve Maintenance Kit -PartNumber
5004052: Thiskitcontainsthepartsnecessarytoreplace
thedeliverycheckvalve.
•Purge Valve Maintenance Kit - Part Number
5018313: This kit contains the parts necessary to
replaceandrelubricatethepurgevalvesealingrings.
•Governor/Delivery Check Valve Kit - Part Number
5004049: Thiskitcontainsthepartsnecessarytoreplace
boththegovernoranddeliverycheckvalve.
•12 volt or 24 volt Heater and Thermostat Kit - Part
Numbers 109495 & 109496: Contains a replacement
heaterandthermostatassemblyandrelatedcomponents
requiredforreplacement.
• Purge Valve Housing Rebuild Kit - Part Number
5003547: Thiskitcontainsthe partsnecessarytorebuild
thepurgevalvesub-assembly.
• Service New Purge Valve Housing Assembly - Part
Number 800404: Contains a service new assembly
andrelatedcomponentstochangethepurgevalvesub-
assembly.
• Pressure Protection Valve Boot Replacement- Part
Number 5005163.
•AD-IS®AirDryerReplacement: Replacesthecomplete
air dryer assembly. Includes air dryer assembly and
governor.
• AD-IS®Air Dryer Splash Shield Replacement Kit -
Part Number 5006698.
• PurgeReservoirDrain Valve: Replacesthedrainvalve
onthepurgereservoir.
SEE THE AD-IS®AIR DRYER CATALOG PAGE
(STARTING ON PAGE 08-A-24) FOR A FULL LIST
OF MAINTENANCE KITS AVAILABLE.
NOTE: Kitsarenotavailablefortheservicingof thepressure
protection valves (See Figure 5). Do not attempt to adjust
or service the pressure protection valves - these are not
service items.
TESTING THE AD-IS
®
AIR DRYER AND
RESERVOIR SYSTEM
Beforeplacing the vehicle inservice, perform the following
tests:
1. Closeallreservoirdrainvalves.
2. 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
approximately30secondsofairflowingoutofthepurge
valve.
3. “Fan” the service brakes to reduce system air pressure
togovernorcut-in.Notethatthesystemonceagainbuilds
tofull pressure andis followed bya purge attheAD-IS®
air dryer and reservoir system exhaust.
4. Itisrecommendedthatthetotal air system be tested for
leakagetoassurethattheAD-IS®airdryerandreservoir
system will not cycle excessively.
SeeBendixpublicationBW5057"AirBrakeHandbook."
BRAKING SYSTEM PROTECTION
TheAD-IS®airdryerandreservoir systemallowsthesystem
tomaintain one brake circuitupto about 100 psieven 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
applicationsbefore the parking brakesautomaticallyapply
and stay on.
ROADSIDE INSPECTION
In the event of a roadside inspection the system behavior
willbeasfollows: When the system is chargedtogovernor
cut-out,andthenonereservoirdrainvalveisopened,initially
bothreservoirgaugeswillfall,however,theAD-IS®airdryer
and reservoir system 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,thefollowingprocedure
needsto be followed:
Followthe Maintenance Precautions outlinedelsewherein
this document.
Make sure that all residual pressure has been released
andtheairdryer purge reservoirhasbeendrainedto0 p.s.i.,
then remove the air supply line from the compressor to the
inlet port (1/IN). Remove the safety valve from theAD-IS®
airdryerandreservoirsystembody(seeFigure1forlocation).
Notethatashortpuffoftrappedair may vent fromthesafety
valveportwhenthe valveisbeingremoved. InstallaT-fitting
into the port. Using any adapters necessary, reinstall the
safety valve in one of the branches of the T-fitting. Using
any adapters necessary, install the air supply line into the
remainingT-fitting port. Aftertesting the T-fitting for any air
leakage, by using a soap solution after charging to system

9
FIGURE 7 - AD-IS®AIR DRYER AND RESERVOIR SYSTEM DELIVERY CHECK VALVE
GOVERNOR GASKET
(SPECIALGASKET,
SEE NOTE 6) GOVERNOR
(NON-ADJUSTABLE,
130 PSI CUT-OUT)
BOLTS
ADAPTER
LARGE
O-RING
SPRING
CHECKVALVE
BODY
SMALL
O-RING
cut-outpressure(a 1” bubble in 10secondsisacceptable),
the vehicle may be returned to temporary service.
Note: This is a temporary bypass of the air dryer, and
full repair of the unit must be carried out at the earliest
opportunity. With the air dryer and reservoir system
removed from the system, contaminants will be entering
theair system: reservoirs will needtobemanually drained
dailyuntiltherepairsare completed. Atendofeachworking
day, park 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 allcontaminants.
If after bypassing the air dryer and reservoir system the
system pressure still does not build, use the following
proceduretoremove,cleanandreinstallthe delivery check
valve.
DELIVERYCHECKVALVECLEANINGPROCEDURE
(Note: This is only required if system pressure does not
build after temporary bypass is completed.)
SeeFigure 7 throughout thisprocedure. Depressurizethe
air brake system following the general safety precautions
outlined elsewhere in this document. Also, always
depressurizethe air dryerpurgereservoir before servicing
the air dryer.
This procedure does not require removal of theAD-IS®air
dryerand reservoir systemfromthe vehicle.
1. Remove the line from the governor and mark for easy
reinstallation.
2. Remove the bolts attaching the governor to theAD-IS®
airdryerandreservoirsystem andretainforreassembly.
3. Remove thegovernorfromtheairdryer. Beawarethata
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
retaintheo-ringfromtheadapter.
4. Thespring/deliverycheckvalvecannowberemoved.
5. Removeandretaintheo-ringfromcheckvalvebody.

10
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 theAD-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 theAD-IS®air dryer.
4. Inspectthedeliverycheckvalve,o-rings,etc.for wear or
damage. Replace if necessary using the check valve
replacement kit available at authorized Bendix parts
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
Bendix supplied barium or silicon grease.
2. Installthiso-ringon the check valve body bysliding the
o-ring over the set of 4 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 4 straight guide lands. When
the spring has been pushed to the correct location, the
checkvalvebodyisdesignedtoholdtheendofthespring
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. Greasetheadapterandtheremaining larger o-ring and
install it onto the fitting.
6. Position the Bendix supplied gasket, then insert the
governormountingboltsthroughthegovernorandtighten
(to125in-lbs). (Note: Do not replace with a standard
compressor/governorgasket.)
7. Reattachlinetothegovernor.
8. Before placing vehicle back into service, check to see
that the system pressure now builds to full operational
pressure.

11
AD-IS®AIR DRYER AND RESERVOIR SYSTEM TROUBLESHOOTING CHART
SYMPTOM
1. Dryer is constantly
“cycling”or purging. A. Test for excessive system leakage. Allowableleakage 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.Repair
or replace as necessary.
B. Build system pressure to governor cut-out. Wait
1 minute for completion of purge cycle. Using
soapsolution at exhaustofpurge 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
valveismalfunctioning:
Buildsystempressuretogovernorcut-outandallow
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
reachesgovernorcut-in. Thepurgevalvewillreturn
to its closed position. The purge reservoir has a
drain valve which is opened by moving the center
leverawayfromitsclosedposition.Openthedrain
valve and wait 10 seconds to allow any residual
purgepressuretobe 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 boss.
Replace the delivery check valve if there is
excessive leakage (exceeding a 1" bubble in 5
seconds).
Regreasethesealontheairdryercartridgebefore
reinstalling. Be sure the drain valve on the purge
reservoir is not leaking before restoring vehicle to
service.
C. Checkgovernor at both “cut-in”and“cut-out”
position for (i) proper pressures and (ii)
excessive leakage at fittings and exhaust.
D. Removeair strainer or fittingfromcompressor
inlet cavity. With compressor unloaded, check
for unloader piston leakage. Slight leakage is
permissible.
A. Excessive system
leakage.
CAUSE REMEDY
B. Defectivedeliverycheck
valve.
C. Defectivegovernor.
D. Compressorunloader
mechanismleaking
excessively.

12
TROUBLESHOOTING CHART (Continued)
SYMPTOM CAUSE REMEDY
D. Replace desiccant cartridge assembly.
D. Desiccantrequires
replacement.
E. Air by-passes desiccant
cartridge assembly.
F. Air dryer not purging.
G. Purge (air exhaust) time
insufficientdue to
excessive system
leakage.
A. Maximum air dryer inlet
temperatureis
exceeded due to
improperdischargeline
length.
B. Air system charged from
outside air source
(outside air not passing
throughairdryer).
C. Excessive air usage -
Air dryer not compatible
with vehicle air system
requirement(Improper
airdryer/vehicle
application).
A. Check for excessive carbon build up in
compressor discharge 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. If system must have outside air fill provision,
outside air should pass through air dryer.
2. Water in vehicle
reservoirs.
C. RefertoBendixAdvancedTroubleshooting Guide
forAir Brake Compressors (BW1971)forproper
applicationof theAD-IS®air dryerandreservoir
system. An extended purge model (AD-ISEP) is
availablefor many higher air usagevehicles,
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.
F. Refer to Symptom 6.
E. If vehicle uses Holset compressor, inspect
feedbackcheckvalve for proper installationand
operation.
G. Refer to Symptom 1.

13
TROUBLESHOOTING CHART (Continued)
SYMPTOM CAUSE REMEDY
C. Refer to Symptom 1, Remedy B.
D. Repair or replace purge valve assembly.
E. Check governor at both “cut-in” and “cut-out”
positionfor (i) proper pressuresand(ii) excessive
leakage at fittings and exhaust.
F. Repairorreplacepurgevalveassembly.
C. DefectiveAD-IS®air
dryerdelivery check
valve.
D. LeakingTurboCut-Off
valve.
E. Defectivegovernor.
F. Leakingpurgevalve
controlpiston quad-ring.
B. Safetyvalve setting too
low (<150 p.s.i.)
C. System pressure too
high (>135 p.s.i.)
D. Excessivepressure
pulsationsfrom
compressor.(Typical
single cylinder type).
A. Test to determine if air is passing through check
valve. Repair or replace. Refer to Symptom 1,
Remedy B.
B. Replacesafetyvalve.
C. Test with accurate gauge. Replace governor if
necessary.
3. Safetyvalveon air dryer
“poppingoff”or
exhaustingair.
A. DefectiveAD-IS®airdryer
and reservoir system
deliverycheckvalve.
D. Increase volume in discharge line. This can be
accomplishedbyaddinga90cubicinch(orlarger)
reservoirbetweenthecompressorandtheAD-IS®
air dryer and reservoir system.
4. Constant exhaust of air
atairdryerpurgevalve
exhaust or unable to
build system pressure.
(Chargemode.)
A. With compressor loaded, apply soap solution
on purge valve exhaust, to test for excessive
leakage. Repair or replace purge valve as
necessary. Refer to Technical Bulletin
TCH-008-040.
B. Referto paragraph 5 ofOperationandLeakage
Tests for heater and thermostat test.
A. Airdryerpurgevalve
leaking excessively.
B. Purgevalvefrozenopen
- faulty heater and
thermostat,wiring,
blownfuse.

14
TROUBLESHOOTING CHART (Continued)
SYMPTOM CAUSE REMEDY
B. Excessive bends in
dischargeline(water
collects and freezes).
C. Pressureprotection
valve(s)in air dryer will
not open.
D. Refer to Symptom 4.
E. Refer to Symptom 7.
B. Discharge line should be constantly sloping
fromcompressorto air dryer withasfewbends as
possible.
C. Replace air dryer (pressure protection valves are
notserviceable).
D. Refer to Symptom 4, Remedy A.
E. Refer to Symptom 7, RemediesAand B.
5. Cannot build system air
pressure. A. Kinked or blocked
(plugged)dischargeline. A. Checktodetermineif airpassesthroughdischarge line. Check for kinks, bends, excessive carbon
deposits, or ice blockage.
6. Air dryer does not purge
or exhaust air. A. Faultyair dryer purge
valve.
B. See Causes B, E, and F
for Symptom #4.
A. After determining air reaches purge valve control
port by installing a T-fitting with a pressure gauge
intothegovernorunloaderport,repairpurgevalve
if necessary.
B. Refer to Symptom 4, Remedies B, E, and F.
Also refer to Symptom 1, Remedy B.
7. Desiccant material
beingexpelledfrom air
dryerpurgevalve
exhaust (may look like
whitish liquid or paste
or small beads.)
A. Faultydryer cartridge.
B. Excessivedryer vibration.
A. ReplaceAD-IS®air dryer cartridge and/orAD-IS®
airdryer.
B. ChecktheAD-IS®air dryermountingforlooseness
ordamage. Repairmountingandreplacecartridge.
8. Unsatisfactory
desiccant life. A. Excessive system
leakage.
B. Wrongvehicle application
forAD-IS®air dryer.
C. Compressorpassing
excessive oil.
A. Refer to Symptom 1, Remedy A.
C. Check for proper compressor installation; if
symptoms persist, replace compressor. Refer to
Bendix Advanced Troubleshooting Guide for Air
BrakeCompressor (BW1971).
A. A slight “pinging” sound may be heard during
systembuildupwhena singlecylindercompressor
is used. If this sound is deemed objectionable, it
can be reduced substantially by increasing the
dischargelinevolume.
This can be accomplished by adding a 90 cubic
inch(or larger) reservoir between thecompressor
and theAD-IS®air dryer and reservoir system.
9. “Pinging”noise
excessiveduring
compressorloaded
cycle.
A. Single cylinder
compressorwith high
pulse cycles.
B. Refer to Symptom 2, Remedy C.

15
A. Compressorfails to
“unload”.
10. The airdryerpurge
piston cycles rapidly in
the compressor
unloaded(non-
compressing)mode.
A. Checkair hose from governor tocompressorfora
missing, kinked or restricted line. Install or repair
air hose.
Repairorreplacecompressorunloader.
TROUBLESHOOTING CHART (Continued)
SYMPTOM CAUSE REMEDY

16
BW2234 © 2007 Bendix Commercial Vehicle Systems LLC All rights reserved. 5/2007 Printed in U.S.A.