S-1694 Service Bulletin/Repair Instructions

Bendix® GSAT® (Global Scalable Air Treatment) Air Dryer Replacement Kits

for Volvo® Trucks

KIT COMPONENTS

See Figure 1. The following components are in the Bendix®

GSAT® (Global Scalable Air Treatment) air dryer kits for

Volvo® trucks:

Item No.
Component
Quantity
1
Air Dryer (Attached)
1
2
Seal
1
Not Shown
Heater
1
Bendix Volvo Kit Part Number: K202684K57

Volvo Kit Part Number: 23771615

Bendix Mack® Kit Part Number: K202685K57

Mack Kit Part Number: 23771617

Item No.
Component
Quantity
3
Air Dryer (Detached)
1
Not Shown
Heater
1
Bendix Volvo Kit Part Number: K273513SC

Bendix Mack Kit Part Number: K273514SC

Item No.
Component
Quantity
4
Air Dryer (CFL Detached) PRI
1
Not Shown
Heater
1
Bendix Volvo Kit Part Number: K273515SC

Bendix Mack Kit Part Number: K273516SC

Item No.
Component
Quantity
5
Air Dryer (CFL Detached) SEC
1
Not Shown
Heater
1
Bendix Volvo Kit Part Number: K273517SC

Bendix Mack Kit Part Number: K275583SC
When replacing air dryer assembly, it is mandatory that

the air dryer cartridge and carbon filter be replaced. For

replacement kit part numbers and instructions, refer to

S-1693, Bendix® GSAT® (Global Scalable Air Treatment)

Air Dryer Cartridge and Filter Kits for Volvo® Trucks,

on B2Bendix.com.
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, a Bendix ® AD-9si ®, AD-HF®,

or AD-HFi ® 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,

fittings, wiring, etc. must be of equivalent size, type and

strength as original equipment and be designed specifically

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 specifically 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.
1
1
2
Air Connection

Port ID
Function/

Connection
Port Size

ISO 4039-2
Maximum

Torque
11 IN
Energy Inlet

Compressor
M22x1.5
29.5+5 ft-lb

(40+7 N•m)
12 IN
Energy Inlet

External Air Fill
M22x1.5
29.5+5 ft-lb

(40+7 N•m)
2.1 DEL
Energy Outlet to

Detached Core

Module
M22x1.5
29.5+5 ft-lb

(40+7 N•m)
4.5 CON
Control Line to

Detached Core

Module
M12x1.5
18+3 ft-lb

(25+5 N•m)
3 EXH
Exhaust
n/a
n/a
M12 Mounting
GSAT to Vehicle

Mounting
M12x1.75
55+11 ft-lb

(75+15 N•m)
Table 1 – Air Connections
DISASSEMBLY

Air Dryer (Attached Variant)

3, 4, 5
NOTE: Identify and mark all air line connections on the air

dryer for reinstallation ease.

1. Disconnect all air line connections from the air dryer.

2. To remove the air dryer from the core module, first remove

the air dryer cartridge to access the mounting bolts from

the air dryer to the core module.
Figure 1 – Air Dryer Kits
DESCRIPTION

IMPORTANT

Do not install the air dryer included in this kit if it does

not match the one being removed.

These kits are used to replace the Bendix® GSAT® (Global

Scalable Air Treatment) air dryer. These are not retrofit

kits. These kits cannot be installed on vehicles that do not

have an existing GSAT system. Be sure to verify the air

dryer included in this kit is identical to the air dryer you

are replacing. Ensure both air dryers have the same port

configuration, heater voltage, and mounting configuration in

the same locations.
VEHICLE PREPARATION

1. Park the vehicle on a level surface and chock the wheels.
3. Using an appropriate filter wrench (if necessary), loosen

the old cartridge and remove it from the air dryer housing

by turning in a counter-clockwise direction. Be careful

not to allow dirt or other contaminants to fall into the air

dryer housing. Discard the cartridge.
IMPORTANT

When replacing air dryer assembly, it is mandatory that

the air dryer cartridge and carbon filter be replaced. For

replacement kit part numbers and instructions, refer to

S-1693, Bendix® GSAT® (Global Scalable Air Treatment)

Air Dryer Cartridge and Carbon Filter Kits for Volvo®

Trucks, on B2Bendix.com.

4. Once accessible, remove the carbon filter from the air

dryer body and discard. See Figure 2.
2. Turn the ignition switch OFF.

3. Drain all reservoirs to 0 psi (0 kpa).
No Carbon Filter
4. Clean the exterior of the air dryer body, cartridge, and

core module silencers to remove any dirt and debris.
Always depressurize all air dryers and air reservoirs on

the vehicle to 0 psi (0 kpa) before servicing the air dryer.

Failure to drain the air pressure from all air dryers and

air reservoirs may result in injury and/or death.

Figure 2 – Carbon Filter
2
Carbon Filter Installed
5. Using a T-30 Torx® drive, remove the four (4) M6 mounting

bolts that secure the air dryer to the core module and

set them aside for reuse.
M6 Mounting

Bolts
5. Clean the mounting surface area of the core module with

a clean cloth and inspect for damage to the mounting

surface.
When replacing air dryer assembly, it is mandatory that

the air dryer cartridge and carbon filter be replaced. For

replacement kit part numbers and instructions, refer to

S-1693, Bendix® GSAT® (Global Scalable Air Treatment)

Air Dryer Cartridge and Carbon Filter Kits for Volvo®

Trucks, on B2Bendix.com.
ASSEMBLY

Air Dryer (Attached Variant)

1. Before mounting the air dryer to the core module, install

the new seal (included in kit) into the seal groove of the

air dryer mounting surface. Ensure the orientation tabs

are located in the correct slots, and fully seat the seal

into the groove.
M6 Mounting

Bolts

Seal
Figure 4 – Seal Installation

Figure 3 – M6 Mounting Bolts
6. Remove and retain the five (5) M12 mounting bolts that

secure the air dryer and attached core module to the

vehicle.

7. The air dryer can now be removed by pulling it away

from the core module, taking care to not damage the

alignment pins and the heater connection. Discard the

seal (a new seal is provided in the kit).

8. Clean the mounting surface area of the core module

with a clean cloth. Be careful not to allow dirt or other

contaminants to fall into the delivery bore of the core

module.

Air Dryer (Detached Variant)

NOTE: Identify and mark all connections on the air dryer for

reinstallation ease.

1. Disconnect all air line connections from the air dryer.

2. Disconnect the heater electrical connector from the air

dryer.

3. Remove and retain the three (3) M12 mounting bolts

that secure the air dryer to the vehicle.
2. Align the air dryer mounting alignment holes with the

alignment pins on the core module. Take care not to

damage the exposed heater connection pins.

3. Seat the air dryer to the core module. The heater pins

of the core module will engage with the air dyer heater.

4. Secure the air dryer to the core module with the four (4)

M6 mounting bolts set aside during disassembly.

5. Using a T-30 Torx drive, torque the air dryer to

the core module mounting screws to 71 in-lbs

(8 N•m) in a cross pattern.

6. Secure the air dryer to the vehicle using the original

five (5) M12 mounting bolts that were removed during

disassembly. Torque to 55 ft-lbs (75 N•m).

7. Connect all of the air connections to the new air dryer

as marked during the disassembly process.

8. Install the new air dryer cartridge and carbon filter per the

installation instruction S-1693, Bendix® GSAT® (Global

Scalable Air Treatment) Air Dryer Cartridge and Carbon

Filter Kits for Volvo® Trucks, which is shipped with the

replacement kit can be found on B2Bendix.com.
4. Remove the air dryer.

3
NOTE: If using a filter wrench, place the filter wrench on

areas A or B as shown in Figure 5 to avoid damage to

the cartridge. If a filter wrench is used in the middle of the

cartridge, damage may occur.

NOTE: When replacing the air dryer cartridge, the cartridge

lifetime wear and wetness content will need to be reset. Use

Bendix® ACom® Diagnostic Software, or a Volvo® diagnostic

tool, to initiate the cartridge reset routines.

9. Before placing the vehicle back into service, perform the

Operational Test.
OPERATIONAL TEST

Before placing the vehicle in service, perform the following

tests.

1. Close all of the reservoir drain cocks.

2. With the engine at 1800 rpm, build up system pressure to

system cutout while observing that both service reservoir

dash gauges rise equally in pressure from 0 psi (0 kpa)

to system cutout. If either gauge fails to display this

condition, stop testing and check the installation. Note

that the Bendix® GSAT® (Global Scalable Air Treatment)

system regenerates/purges with an audible escape of

air when system cutout pressure is reached.

NOTE: The service reservoir pressures will drop during

regeneration/purge.

3. Fan down the service brakes to reduce system air

pressure to system cut-in. Note that the system – once

again – builds to full system pressure and is followed

by a regeneration/purge event at the GSAT air dryer

primary exhaust.
Figure 5 – Air Dryer Cartridge Filter Wrench Placement
Air Dryer (Detached Variant)

1. Secure the air dryer to vehicle using the original three

(3) M12 mounting bolts that were removed during

disassembly. Torque to 55 ft-lbs (75 N•m).
4. To verify proper park brake function, use the Hand Control

Unit (HCU) to release and apply the tractor park brakes

several times. The HCU and/or dash cluster should

illuminate, indicating a proper park state.

5. It is recommended that the following items be tested for

leakage to ensure the GSAT will not cycle excessively:
2. Connect all air connections to the new air dryer as marked

during the disassembly process.
a. A

 ir brake system (Refer to the Bendix® Air Brake

Handbook, BW5057, on B2Bendix.com)
3. Install the new air dryer cartridge and carbon filter per the

installation instruction S-1693, Bendix® GSAT® (Global

Scalable Air Treatment) Air Dryer Cartridge and Carbon

Filter Kits for Volvo® Trucks, which is shipped with the

replacement kit can be found on B2Bendix.com.
b. C

 ompressor unloader mechanism per manufacturer's

recommendation
NOTE: If using a filter wrench, place the filter wrench on

areas A or B as shown in Figure 5 to avoid damage to

the cartridge. If a filter wrench is used in the middle of the

cartridge, damage may occur.

NOTE: When replacing the air dryer cartridge, the cartridge

lifetime wear and wetness content will need to be reset. Use

Bendix ACom Diagnostic Software, or a Volvo diagnostic

tool, to initiate the cartridge reset routines.

4. Before placing the vehicle back into service, perform the

Operational Test.
24/7/365 ACCESS

FULL SERVICE AT YOUR FINGERTIPS
  
1-800-AIR-BRAKE (1-800-247-2725)

TECHTEAM@BENDIX.COM
c. GSAT core module

d. D

 rain cock and safety valve in first (supply) reservoir,

(if equipped)

e. A

 ll air connections leading to and from the first

(supply) reservoir (if equipped)
TECHNICAL ASSISTANCE

For additional assistance, the Bendix Tech Team can

be reached by email at techteam@bendix.com or by

phone at 1-800-AIR-BRAKE (1-800-247-2725), option 2.

Representatives are available Monday through Thursday,

8:00 

a.m. – 6:00 p.m., and Friday, 8:00

a.m. – 5:00 p.m.

 ET.

24/7/365 ACCESS

FULL SERVICE AT YOUR FINGERTIPS
1-800-AIR-BRAKE (1-800-247-2725)

TECHTEAM@BENDIX.COM
   
WEB-BASED TRAINING

LOG ON AND LEARN FROM THE BEST
Any references in this document to VOLVO, MACK, and any other company or trademark

are solely for identification and cross reference purposes.

Unless otherwise indicated, the trademarks used in this document, including Bendix,

are United States trademarks owned by, or licensed to, Bendix Commercial Vehicle Systems LLC.
4
S-1694 Rev 004 © 12/2025 Bendix Commercial Vehicle Systems LLC, a member of Knorr-Bremse • All Rights Reserved

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