Bosch ACS 255 User manual

ACS 255
en Original instructions
A/C service unit

F 002 DG9 432 2014-12-19|Bosch Limited
| ACS 255 | 3 en
Contents English
1. Symbols used 4
1.1 In the documentation 4
1.1.1 Warning notices - Structure and
meaning 4
1.1.2 Symbols in this documentation 4
1.2 On the product 4
2. User information 5
2.1 User group 5
2.2 Agreement 5
2.3 Obligation of contractor 5
2.4 Safety Instructions 5
2.5 Safety devices 6
3. Product description 7
3.1 Application 7
3.2 Delivery specification 7
3.3 Description of unit 7
3.3.1 Human Machine Interface (HMI) 8
3.3.2 Scale for refrigerant tank 8
3.3.3 Oil bottles 8
3.3.4 Quick couplers 9
3.3.5 Brakes 9
3.3.6 Power cable and master switch 9
3.4 Description of function 9
4. Commissioning 10
4.1 Removing the transport packaging 10
4.2 Before turning on for the first time 10
4.3 Powering on the ACS 255 11
4.4 Changing the system defaults 11
4.5 Filling the internal refrigerant
tank 12
4.6 Viewing system information 12
5. Troubleshooting 13
6. Program description 14
6.1 ACS 255 operating modes 14
6.2 Preparations for A/C service 14
6.3 Configuring the custom database 14
6.3.1 Adding new vehicle details to the
vehicle database 14
6.3.2 Editing vehicle details in the custom
database 14
6.3.3 Deleting vehicle details from the
custom database 14
6.3.4 Viewing custom database information 14
6.3.5 Transferring the custom database
from one ACS 255 to another 14
6.4 Accessing the custom database 14
6.5 Automatic mode 15
6.5.1 Overview of automatic mode 15
6.5.2 Selecting the vehicle from the
custom database 15
6.5.3 Setting custom parameters 15
6.6 Manual mode 15
6.6.1 Overview of manual mode 15
6.6.2 Recovery 16
6.6.3 Vacuuming phase 16
6.6.4 Oil recharge phase 16
6.6.5 Recharge phase 16
6.7 Performing service in manual mode 16
6.8 Additional services 17
6.8.1 Refrigerant top up 17
6.8.2 Hose drain 17
6.8.3 A/C performance test 17
7. Maintenance 18
7.1 Spare and wearing parts 18
7.2 Refilling the refrigerant tank 18
7.3 Service record 18
7.3.1 Viewing the last three vehicle A/C
service reports 18
7.3.2 Last self test 18
7.3.3 Last five errors during vehicle A/C
service 18
7.4 Vacuum pump oil change 18
7.5 Replacing the filter drier 19
7.6 Replacing the inline filters 19
7.7 Self test 20
7.8 Firmware update 20
7.9 Resetting factory settings 20
8. Decommissioning 21
8.1 Disposal of electronic items 21
8.2 Disposal of LCD display, refrigerants,
lubricants and oils 21
8.3 Disposal of filter drier 21
8.4 Electromagnetic compatibility (EMC) 21
9. Technical data 21

F 002 DG9 432 2014-12-19| Bosch Limited
4 | ACS 255 | Symbols useden
1. Symbols used
1.1 In the documentation
1.1.1 Warning notices - Structure and meaning
Warning notices warn of dangers to the user or people
in the vicinity. Warning notices also indicate the con-
sequences of the hazard as well as preventive action.
Warning notices have the following structure:
Warning
symbol
KEY WORD – Nature and source of hazard!
Consequences of hazard in the event of fail-
ure to observe action and information given.
¶Hazard prevention action and information.
The key word indicates the likelihood of occurrence and
the severity of the hazard in the event of non-obser-
vance:
Key word Probability of
occurrence
Severity of danger if in-
structions not observed
DANGER Immediate impending
danger
Death or severe injury
WARNING Possible impending
danger
Death or severe injury
CAUTION Possible dangerous
situation
Minor injury
1.1.2 Symbols in this documentation
Symbol Designation Explanation
!Attention Warns about possible property dam-
age.
iInformation Practical hints and other useful in-
formation.
1.
2.
Multi-step
operation
Instruction consisting of several
steps.
eOne-step oper-
ation
Instruction consisting of one step.
 Intermediate re-
sult
An instruction produces a visible in-
termediate result.
"Final result There is a visible final result on com-
pletion of the instruction.
1.2 On the product
!Observe all warning notices on products and ensure
they remain legible.
Caution!
Contact with the refrigerant can cause
blindness and severe injuries.
¶Read this operating manual and all
technical documentation for the used
components.
¶Wear protective gloves.
¶Wear protective goggles.

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User information | ACS 255 | 5 en
2. User information
2.1 User group
The product may be used by skilled and instructed
personnel only. Personnel scheduled to be trained, fa-
miliarized, instructed or to take part in a general train-
ing course may only work with the product under the
supervision of an experienced person.
All work conducted on pressurized equipment may be
performed by persons with sufficient knowledge and
experience in using pressurized devices and, also be
aware of the risks involved in the use of pressurized
devices.
2.2 Agreement
Your use of the product means that you accept the fol-
lowing conditions:
Copyright
Software and data are the property of Bosch Limited,
hereafter denoted as Bosch, or its suppliers and are
protected against unauthorized reproduction under
copyright laws, international contracts and other na-
tional legal provisions. Copying and selling of data
and software or any other part thereof is prohibited
and punishable by law. In the event of violations,
Bosch Limited reserves the right to proceed with crimi-
nal prosecution and to claim for damages.
Liability
All data in this program is based - where possible - on
manufacturer and importer details. Bosch does not ac-
cept liability for the correctness and completeness of
software and data; liability for damage caused by faulty
software and data is ruled out. Whatever the event,
Bosch liability is restricted to the amount for which the
customer actually pays for this product. This disclaimer
of liability does not apply to damages caused by intent
or gross negligence on the part of Bosch.
Warranty
Any use of non-approved hardware and software will
result in a modification to our product and thus to
exclusion of any liability and warranty, even if the hard-
ware or software has in the meantime been removed or
deleted. No changes may be made to our products. Our
products may only be used in combination with original
accessories and original service parts. Failing to do so,
will render null and void all warranty claims.
2.3 Obligation of contractor
The contractor is obliged to ensure that all measures
geared towards the prevention of accidents, industrial
diseases, labor-related health risks are taken and mea-
sures towards making the workplace fit for people to
work in are carried out.
The contractor is bound to ensure that all electrical
equipment and operating material is set up, modified
and maintained by skilled electricians only or under the
guidance and supervision of a skilled electrician in ac-
cordance with electrical engineering principles.
Furthermore, the contractor must ensure that all elec-
trical equipment and operating material is operated in
keeping with electrical engineering principles.
If a piece of electrical equipment or operating material
is found to be defective, i.e. it does not or no longer
complies with electrical engineering principles, the con-
tractor must ensure that the fault is rectified immedi-
ately and, in the event that imminent danger exists, also
ensure that the electrical equipment or the electrical
operating material is not used.
2.4 Safety Instructions
All safety instructions are to be read thoroughly before
using the Bosch product and they must be observed.
RAvoid the refrigerant coming into contact with the
skin. The low boiling point of the refrigerant (approx-
imately -30 °C at atmospheric pressure) can cause
frostbite. In case of contact with the skin, remove
wet clothing immediately and rinse the affected area
of skin with plenty of water.
Do not breathe in refrigerant or oil vapors.
The vapors can irritate the eyes and the
breathing passage of the nose. If liquid
refrigerant/oil gets into the eyes, rinse the
eyes thoroughly with water for 15 minutes.
Then, seek medical attention, even if the
eyes do not hurt.
RBefore the ACS 255 is connected to the vehicle A/C
system or to an external refrigerant tank, ensure that
the quick couplers do not leak. Use only external
refrigerant tanks that are fitted with safety valves
and approved in accordance with the applicable
standards.
RBefore turning off the ACS 255, ensure that all the
service phases are complete. This prevents refriger-
ant from escaping into the environment.

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6 | ACS 255 | User informationen
Do not use compressed air with R134a.
Some mixtures of air and R134a are highly
flammable at high pressure. These mixtures
are potentially hazardous and can cause
fires or explosions resulting in damage to
property and injury to persons.
RRefrigerant extracted from the vehicle A/C system
might be contaminated with moisture, lubricant, dirt
and traces of other gases.
RThe ACS 255 does not have any refrigerant identifier
system. If refrigerants other than R134a are used, it
might lead to contamination.
RR134a is colorless, odorless and heavier than air. It
expels oxygen and can flow into repair pits. If the
refrigerant escapes, there is a risk of suffocation in
poorly ventilated rooms or repair pits.
RR134a may not be used in environments with a risk
of explosion. Fire, naked flames and smoking are
prohibited. No welding or soldering is allowed. High
temperatures and UV radiation can cause R134a to
chemically separate. The resulting products cause
coughs and nausea.
RR134a may not be mixed with other refrigerants.
Mixing refrigerants can cause damage to the vehicle
A/C system.
RThe ACS 255 must always be monitored during op-
eration. Do not leave the ACS 255 unattended when
it is switched on.
RVehicle A/C service, using the ACS 255, must be pre-
pared and carried out in such a way that the vehicle
A/C circuit is not opened (for example, radiator or
engine removal).
RThe ACS 255 should be positioned with all four
wheels on a flat, vibration-free surface to ensure
correct operation of the load sensors. The ACS 255
can be prevented from rolling away by applying the
brake.
RThe ACS 255 must always be transported in a verti-
cal position. Do not invert the ACS 255.
RThere are no additional safety provisions for protect-
ing the ACS 255 unit against damage in the event of
natural calamities like earthquakes, fires, floods etc.
RExcept for maintenance work, do not remove any
pressurized equipment inside the
ACS 255 unit. Adhere to the national laws or regula-
tions for ensuring safety of pressurized equipment.
RWe recommend that calibration of load sensors be
done at least once every year. Contact customer
service for calibration of load sensors.
RThe ACS 255 must be regularly inspected by service
personnel or the approved authorities to ensure
safety of the unit.
Warning - Risk of frostbite in the event of
refrigerant leakage!
If refrigerant escapes, there is a risk of frost-
bite to the hands and body.
¶Wear protective goggles.
¶Wear protective gloves.
¶Ensure that the HP and LP hoses are not
damaged.
¶Ensure that the quick couplers are tightly
fixed to the hoses.
Warning - Risk of frostbite during removal
of service hoses!
If refrigerant escapes, there is a risk of
frostbite to the hands and body.
¶Carefully disconnect service hoses as all
hoses can contain pressurized
refrigerant.
ROnly connect to a properly grounded electrical
outlet.
RDo not attempt to shut off the valves on the R134a
tank when the ACS 255 is in operation.
RFor the purposes of safety, it is recommended to use
an Earth Leakage Circuit Breaker (ELCB) with the
following specifications:
Parameter Specification
Rated voltage 230 VAC +/- 10%
Rated frequency 50/60 Hz
Rated current 10 A
Rated trip current 30 mA
Tripping curve C
2.5 Safety devices
RPressure switch - Switches the compressor off if the
normal operating pressure is exceeded.
RSafety valve: Operates when the design pressure is
exceeded.
RFuse: Interrupts excessive current flow into the
ACS 255.

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Product description | ACS 255 | 7 en
3. Product description
3.1 Application
The ACS 255 is used to perform the following basic
services for passenger car A/C systems in manual or
automatic mode:
RRefrigerant recovery
ROil recharge
RVacuuming and leak tests
RRefrigerant recharge
The ACS 255 should be used with car A/C systems that
use R134a.
3.2 Delivery specification
Description
ACS 255
Hose - HP
Hose - LP
Quick coupler - HP
Quick coupler - LP
Can assembly - Used oil
Can assembly - Fresh oil
Operating instructions
Adapter for filling internal refrigerant tank
3.3 Description of unit
459897_159Nkv
123
4
5
6
7
8
9
11
14
12
13
10
15
Fig. 1: Front view
1 Handle (x 2)
2 HP gauge
3 Status and warning light
4 LP gauge
5 LCD
6 Keypad
7 LP hose
8 HP hose
9 Fresh oil bottle
10 Front panel
11 Front wheels
12 Rear wheel (x 2)
13 Used oil bottle
14 Left-hand side panel
15 Master switch

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8 | ACS 255 | Product descriptionen
1
3
459897_112Nkv
4
5
6
2
7
8
9
Fig. 2: Rear view
1 HMI support
2 Painel superior
3 Power cable
4 Cable holder
5 Rear panel
6 Brakes
7 Right-hand side panel
8 Hose holder
9 USB port
3.3.1 Human Machine Interface (HMI)
The HMI consists of:
RPressure gauges - The pressure during the service is
displayed on the gauges.
RStatus and warning lights - The status of service
and disruptions during service are indicated by the
status and warning light.
Color indicated by the
status and warning light
Status of service
Red Error/Warning
Blinking green Service in progress
Static green Service complete
RLCD - The menu options and status of service are
displayed on the LCD.
RKeypad - The selection of service menu options and
service parameters can be done via the keypad. The
alphanumeric input keys can be used to enter letters
and special characters in input fields. In an input
field, pressing a key several times in succession
displays all the characters it can be used for (upper
case letters, special characters).
iThe alphabetical entries can be made in upper case
only.
Keys Description

c
Function keys,
The function keys are assigned various func-
tions in the ACS 255 software. The functions of
the keys are specified in the soft key bar of the
ACS 255 software.
o or u Navigate up or down
vor zNavigate right or left
EEnter
CClear
Switch between numeric and alphabetical entry
iDisplay system information
RUSB port - Firmware updates can be performed by
plugging the USB disk into the USB port.
3.3.2 Scale for refrigerant tank
The quantity of refrigerant charged into the vehicle A/C
system is controlled by a scale mounted beneath the
refrigerant tank.
3.3.3 Oil bottles
!Do not apply excessive force while detaching or at-
taching the oil bottles.

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Product description | ACS 255 | 9 en
459897_108Nkv
1
Fig. 3: Detaching the fresh oil bottle
1 Connector
To detach the fresh oil bottle, pull the connector
(Fig. 3, Pos. 1) slightly downwards and pull down the
bottle.
459897_109Nkv
1
Fig. 4: Detaching the used oil bottle
1 Connector
To detach the used oil bottle, pull the connector
(Fig. 4, Pos. 1) slightly upwards and pull down the
bottle.
Observe the symbols on the front panel to identify the
bottles. The following table lists the symbols and their
description.
Symbol Description
Fresh oil bottle
Used oil bottle
3.3.4 Quick couplers
The quick couplers (see fig. 8) are connected to the
service connections on the vehicle A/C system to per-
form the service. To detach the quick couplers from
the service connection on the car A/C system, grip the
knurled portion of the coupler. Depress the coupler
slightly and pull back the knurled portion gently to re-
lease the coupler.
To attach the coupler to the service connection on the
vehicle A/C system, place the coupler on the service
connection and pull back the knurled portion of the
coupler. Press gently.
3.3.5 Brakes
The ACS 255 can be prevented from rolling away by ap-
plying brakes (Fig. 2, Pos. 6) on the rear wheels.
3.3.6 Power cable and master switch
The power cable is connected to the inlet and then to
the mains supply. When not in use, the power cable
can be wound on the cable holder (Fig. 2, Pos. 4). The
ACS 255 can be powered on by turning the switch in
the clockwise direction.
3.4 Description of function
The functions performed by the ACS 255 are:
RRecovery and recycling - Refrigerant is recovered
from the car A/C system. It is then recycled to
remove suspended particles and moisture. The
cleaned refrigerant is stored in the refrigerant tank.
RVacuuming and leak detection - A deep vacuum is
created and car A/C system is checked for leaks.
RRecharging refrigerant - The refrigerant in the refrig-
erant tank is charged into the vehicle A/C system.
RReplenishing vehicle compressor oil along with re-
frigerant as specified by the vehicle manufacturer

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10 | ACS 255 | Commissioningen
4. Commissioning
iAll the operations described in chapter 4 must be
performed prior to initial vehicle A/C system
servicing.
4.1 Removing the transport packaging
1. Remove the transport packaging.
2. Remove the components placed beneath the
ACS 255.
3. Move the ACS 255 out of the packaging palette.
4. Disconnect the power cable from the power inlet.
!Do not disconnect electrical connections or tamper
with the internal components. If there is any damage
or oil spillage, contact customer service.
1
459897_113Nkv
2
3
Fig. 5: Opening the rear panel
1 Refrigerant tank
2 Rear panel
3 Red and blue knobs
5. Open the rear panel (Fig. 5, Pos. 2).
6. Ensure that the red and blue knobs on the refriger-
ant tank are open.
7. Close the rear panel.
4.2 Before turning on for the first time
1. Remove the hoses, HP and LP couplers from the
packaging box.
2. Apply the brakes on the rear wheels.
3. Open the front panel.
4. Open the screw cap of the vacuum pump
(Fig. 6, Pos. 1).
1
2
459897_115Nkv
3
4
Fig. 6: Filling vacuum pump oil
1 Screw cap
2 Sight glass
3 Drain plug
4 Level indicator
5. Observe the oil level in the vacuum pump sight glass
(Fig. 6, Pos. 2). If the oil quantity is inadequate,
open the screw cap of the vacuum pump.
6. Top up the oil.
iEnsure that you use VPO46 High vacuum pump oil.
The maximum quantity of oil that can be filled is
400 ml.
7. Close the screw plug of the vacuum pump.
8. Close the front panel.
9. Fix the oil bottles to the connectors.

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Commissioning | ACS 255 | 11 en
2
1
3
459897_114Nkv
4
Fig. 7: Connecting the service hoses
1 Hose connection
2 Service hose end connection
3,4 Identification for HP and LP hose connection
10. Connect the end connectors of the service
hoses (Fig. 7, Pos. 2) to the hose connections
(Fig. 7, Pos. 1). Observe the red / blue identifica-
tion stickers on the front panel before connecting
the hoses. Tighten the hose connection.
!Tighten the service hose end connectors by hand. Do
not use any tools.
iThe HP hose (red hose) should be connected to the
hose connection with the red identification sticker
(Fig. 7, Pos. 4). The LP hose (blue hose) should be
connected to the hose connection with the blue
identification sticker (Fig. 7, Pos. 3). Do not inter-
change the HP and LP hose connections.
459897_124Nkv
2
1
Fig. 8: Fixing the couplers to the hoses
1 Coupler
2 O-ring
11. Insert the coupler unto the hoses and tighten.
Ensure that the O-rings used for connecting the
couplers to the hoses are properly placed before
tightening the coupler.
4.3 Powering on the ACS 255
1. Move the ACS 255 to a flat, vibration-free surface.
2. Apply the brake to prevent the unit from rolling away.
3. Connect the power cable to the power inlet of the
ACS 255.
4. Connect the power cable to the mains supply.
iRefer chapter 9 for the specifications of power supply.
5. Turn on the master switch.
The self-test is initiated automatically. After the
self test is complete, the "Date and Time" screen
is displayed.
iWhen the unit is powered on for the first time, the
ACS 255 starts in English.
6. Enter the date in the format dd.mm.yy.
7. Enter the time. Press E.
A list of languages is displayed.
8. Select your language with oor u
(e.g. for English select "English").
9. Press E to confirm the language selected.
10. Enter your workshop data. Press oor uto switch
between fields.
iA maximum of 27 characters can be entered.
11. Press E.
"The main menu is displayed.
4.4 Changing the system defaults
If the system defaults are not set, the default values of
the parameters set at the factory will be used during
automode service.
iRefer to the vehicle documentation for the values of
the parameters.
To change the default settings, execute the following
procedure.
1. From the main menu, select "ACS Settings" >> "Sys-
tem Defaults".
2. Press E.
3. Set the automode service parameters. To set the
default values again, press .
"The system defaults are set.

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12 | ACS 255 | Commissioningen
4.5 Filling the internal refrigerant
tank
Before the ACS 255 can be used, the internal refriger-
ant tank must be filled with R134a.
The refrigerant can be procured from the local gas sup-
plier. The refrigerant is normally stored and transported
in tanks with connection fittings.
If cylinders without dip tube are used, the liquid ports
of the external cylinders should be connected to the
internal refrigerant cylinder. The cylinder should be
placed in an inverted position during the filling process.
If external cylinders with dip tube are used, the cylin-
ders can be placed in an upright position.
1. Power off the ACS 255.
2. Disconnect the power cable from the mains supply.
3. Apply the brakes on the rear wheel.
4. Connect the adapter to the connection on the
external refrigerant tank.
5. Connect the HP quick coupler of the ACS 255 to the
connecting adapter on the external refrigerant tank.
6. Open shut off valves on the external refrigerant tank.
The pressure of the external refrigerant tank is
displayed on the HP manometer.
7. Connect the power cable to the mains supply.
8. Turn on the master switch.
9. In the main menu select "Vehicle A/C Service" >>
"Additional Services" >> "Internal Bottle Fill". Alter-
nately, press c and select "Additional Services" >>
"Internal Bottle Fill".
iTo ensure reliable operation, it is recommended to
use the optimum refrigerant quantity. The optimum
refrigerant quantity for the ACS 255 is 4 kg - 7 kg.
If the quantity is too less, you may not be able to
recharge the refrigerant during service. If the quan-
tity is too high, you may not be able to recover the
refrigerant during service.
10. Enter the quantity of R134a to be filled and
press E.
The filling of the internal refrigerant tank starts.
11. After the internal refrigerant tank is filled, close the
valves on the external refrigerant tank. Press .
12. Disconnect the adapter from the external tank.
Press .
13. Press to execute the hose drain.
"After the hose drain is completed, the internal refriger-
ant tank is filled. The quantity of refrigerant filled is
displayed.
4.6 Viewing system information
¶Press the ikey.
"The system information is displayed.
iTo dismiss the information screen, press the ikey
again.

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Troubleshooting | ACS 255 | 13 en
5. Troubleshooting
Error code Messages Actions
1001 RECOVERY - Service Timeout Check for blockage in the vehicle A/C system.
1004 RECOVERY - Internal Tank full RWeight limit reached. Reduce quantity of refrigerant in refrigerant tank.
RLoad cell is defective. Contact customer service.
100A RECOVERY - Low pressure in A/C REnsure quick couplers are connected properly to the service ports on the vehi-
cle A/C system.
RIf the couplers are connected properly, try to perform A/C service. If the error
persists, contact customer service.
2001 VACUUMING - Perform Recovery The pressure is greater than 1400 mbar while vacuuming:
RContinue the recovery.
RAbort the recovery.
2002 VACUUMING - Leak Detected Repair the vehicle A/C system.
5001 R134A RECHARGE - Service
Timeout
RCheck for blockage in the ACS 255.
RCheck if quick couplers are open.
5002 R134A RECHARGE - Insufficient
R134a
Fill the internal refrigerant tank.
5005 R134A RECHARGE - Internal Tank
full
RWeight limit reached. Reduce quantity of refrigerant in internal refrigerant tank.
RLoad cell is defective. Contact customer service.
5006 R134A RECHARGE - Perform
Recovery
RContinue the recovery.
RAbort the recovery.
5007 R134A RECHARGE - Perform
Vacuuming
Perform vacuuming.
7100 Safety Switch - SS shutdown RAllow the unit to cool for 30 minutes and switch on the ACS 255. Try recovery/
hose drain.
RCheck if the blue knob on the refrigerant tank is closed. Open the blue knob If
it is closed.
RContact customer service if the problem persists.
7302 PS - Sensor failure RContact customer service.
RFor error messages 7501, 7502, 7503, 8000 and C001, contact customer ser-
vice
9102 FACTORY SETTING - Not
Complete
RSelf-test failed. See the self test report and take corrective action.
A101 TANK FILL - Service Timeout Check for blockage in the ACS 255.ACS 255..
A103 TANK FILL - Internal Tank full RWeight limit reached. Reduce quantity of refrigerant in refrigerant tank.
RLoad cell is defective. Contact customer service.
A105 TANK FILL - Check Ext. valve RCheck if the valve on the external tank is open.
RCheck if R134a is available in the external tank.
A601 R134a TOP UP - Service Timeout RCheck if the vehicle A/C system is on.
RCheck for blockage in the ACS 255.
RCheck the refrigerant tank scale.
RCheck for blockage in the hoses
A602 R134a TOP UP - Insufficient
R134a Quantity
RCheck if the vehicle A/C system is on.
RCheck for blockage in the ACS 255.
C002 OIL RECHARGE - Perform Recovery The pressure is greater than 1400 mbar while recharging. Perform recovery.
C003 OIL RECHARGE - Perform
Vacuuming
The pressure is greater than 900 mbar while recharging. Perform vacuuming.
C005 OIL RECHARGE - AC high
pressure
RCheck if the fresh oil bottle is connected
RContact customer service
D003 PERFORMANCE TEST - Perform
Hose drain
The pressure is greater than 1400 mbar. Perform hose drain.
iThe message "Service Timeout" indicates the service timeout for any service phase which is in progress. The
following table indicates the service timeout duration for different service phases.
Service phase Timeout duration (mins)
Refrigerant recovery 120
Recharge oil 6
Service phase Timeout duration (mins)
Recharge refrigerant 15
Hose drain 5

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14 | ACS 255 | Program descriptionen
6. Program description
6.1 ACS 255 operating modes
The software in the ACS 255 provides the following
possibilities for performing vehicle A/C service:
RAutomatic mode - In the automatic mode, all the
phases in the A/C service are executed in sequence
automatically.
RManual mode - In the manual mode, only the select-
ed phase is executed. For example, upon selecting
"Recovery", only the recovery phase will be
executed.
6.2 Preparations for A/C service
!The ACS 255 should not be used for servicing a vehi-
cle A/C system that has been repaired with a chemi-
cal sealant. The sealant could damage the ACS 255
and the vehicle A/C system. Non-compliance invali-
dates the warranty.
Before servicing the vehicle A/C system, execute the
following preparatory procedure:
1. Move the ACS 255 to a flat vibration-free surface
close to the vehicle.
2. Apply the brakes to prevent the ACS 255 from rolling
away.
Caution!
Hot engine parts can cause severe burns to
the hands.
¶Allow the engine to cool down before
work.
3. Connect the power cable to the mains supply.
4. Turn on the master switch.
6.3 Configuring the custom database
The ACS 255 features a programmable database, to
which a maximum of 50 vehicles can be added. The ve-
hicle model and R134a quantity for the vehicles can be
entered at the workshop.
iRefer to the vehicle documentation for the service
parameters and other vehicle details.
To configure the custom database:
¶In the main menu, select ACS Settings >> Custom
Database.
6.3.1 Adding new vehicle details to the vehicle
database
1. Select New.
2. Enter the following details:
$Model name
$R134a quantity
3. Press Eto confirm.
"The vehicle details are added to the custom database.
6.3.2 Editing vehicle details in the custom database
1. Select Edit.
The vehicles in the custom database are dis-
played.
2. Select the required vehicle and press E.
3. Edit the vehicle details.
4. Press Eto confirm.
"The vehicle details are edited.
6.3.3 Deleting vehicle details from the custom
database
1. Select Delete.
2. Select the required vehicle and press E.
"The vehicle details are deleted from the custom
database.
6.3.4 Viewing custom database information
It is possible to view the number of vehicles stored and
the number of entries available in the custom database.
¶To view the custom database information select Info.
"The number of entries used and the number of entries
available in the custom database are displayed.
6.3.5 Transferring the custom database from one
ACS 255 to another
iBosch does not accept any liability for the integrity
of data transferred from an ACS 255 to another.
It is also possible to transfer the entries in the custom
database from an ACS 255 to another. Contact Bosch
customer service.
6.4 Accessing the custom database
1. In the main menu, select "Vehicle A/C Service" >>
"Custom Database" and press E. Alternatively,
press  and select "Custom Database".
2. Select the vehicle and press E. Alternatively, enter
the vehicle model name.
"The vehicle model and the R134a quantity are dis-
played.

F 002 DG9 432 2014-12-19|Bosch Limited
Program description | ACS 255 | 15 en
6.5 Automatic mode
6.5.1 Overview of automatic mode
Serviços em modo automático podem ser realizados
das seguintes maneiras:
RSeleção do veículo a partir do banco de dados per-
sonalizado
RDefinição de parâmetros personalizados
6.5.2 Selecting the vehicle from the custom data-
base
!Use only new oil to replace the amount removed dur-
ing the recovery process. Used oil should be discard-
ed as per applicable regulations.
iBefore starting the service, refer to chapter 6.2.
1. Execute the procedure in chapter 6.4 to access the
vehicle database.
2. Press E.
The automode parameters are displayed.
iTo change the automode parameters, refer to
chapter 4.5.
3. Check the type of service connection on the vehicle
A/C system.
!Do not use any tools to tighten the couplers.
4. Connect the appropriate coupler/s to the service
connection on the vehicle A/C system.
5. Press E.
The service begins in the automatic mode. Each
phase is executed automatically. After the ser-
vice is complete, the Hose Drain menu is dis-
played.
6. Turn the HP/LP quick couplers in the counterclock-
wise direction disconnect from the service connec-
tions on the vehicle A/C system.
7. Press E.
8. Press Eto start draining refrigerant from the
hoses.
Once the refrigerant is drained, a summary
screen is displayed.
"The servicing of the vehicle A/C system is complete.
6.5.3 Setting custom parameters
iOnce set, custom parameters are valid only for a
single service.
iBefore starting the service, refer to chapter 6.2.
iRefer to the vehicle-specific documentation for the
A/C service parameters.
!Use only new oil to replace the amount removed dur-
ing the recovery process. Used oil should be discard-
ed as per applicable regulations.
1. In the main menu, select "Vehicle A/C Service" >>
"Automatic Mode" >> "Custom Parameters". Alter-
natively, press  and select "Custom Parameters".
The automode service parameters are displayed.
iTo change the automode parameters, refer to
chapter 4.4.
2. Check the type of connection on the vehicle
A/C system.
!Do not use any tools to tighten the couplers.
3. Connect the appropriate coupler/s to the service
connection on the vehicle A/C system.
4. Press E.
The service begins in the automatic mode. Each
phase is executed automatically. After the service
is complete, the Hose Drain menu is displayed.
5. Turn the HP/LP quick couplers in the counterclock-
wise direction disconnect from the service connec-
tions on the vehicle A/C system.
6. Press E.
7. Press Eto start draining the refrigerant from the
hoses.
Once the refrigerant is drained, a summary screen
is displayed.
"The servicing of the vehicle A/C system is complete.
6.6 Manual mode
6.6.1 Overview of manual mode
In the manual mode, only the selected phase is ex-
ecuted. For example, upon selecting "Recovery", only
the recovery phase will be executed. It is also possible
more than one service phase.

F 002 DG9 432 2014-12-19| Bosch Limited
16 | ACS 255 | Program descriptionen
The default values of the parameters in each stage are
listed in the following table:
Service phase Parameter Default value
Recovery Pressure increase time 1 min
Vacuum Vacuum time 20 min
Vacuum hold time 4 min
Oil recharge Refrigerant quantity 500 g
10 ml
Oil quantity
Tab. 1: Default values of parameters
6.6.2 Recovery
In the recovery phase, the following parameters can be
set:
RDuration for the pressure increase test
RHose selection
$HP hose
$LP hose
$HP and LP hoses
6.6.3 Vacuuming phase
In the vacuuming phase, the following parameters can
be set:
RVacuum creation time
RVacuum test time
RHose selection
$HP hose
$LP hose
$HP and LP hoses
iEnsure that you perform recovery before the vacu-
uming.
6.6.4 Oil recharge phase
In the oil recharge phase, the following parameters can
be set:
ROil quantity
RRefrigerant quantity
RHose selection
$HP hose
$LP hose
$HP and LP hoses
iOil injection can only be carried out on an A/C sys-
tem that is under vacuum.
iEvery time oil is recharged, R134a is also recharged.
iThe quantity of oil added to the vehicle A/C system
corresponds to the quantity drawn during the recov-
ery phase. When filling a vehicle A/C system for the
first time, refer to the vehicle documentation or the
vehicle-specific repair manual for the specified oil
recharge quantity.
iUse oil grade specified by the vehicle manufacturer.
Use only new oil to replace the oil removed during
the recovery process. Used oil should be discarded
as per local regulations.
6.6.5 Recharge phase
In the recharge phase, the following parameters can be
set:
RRefrigerant quantity
RHose selection
$HP hose
$LP hose
$HP and LP hoses
6.7 Performing service in manual mode
!Use only new oil to replace the amount removed dur-
ing the recovery process. Used oil should be discard-
ed as per applicable regulations.
1. In the main menu, select "Vehicle A/C Services" >>
"Manual Mode". Alternatively, press .
The phases that can be executed in the manual
mode are displayed on the screen.
2. Press the oor ukeys to scroll to a particular phase.
To select a particular phase or multiple phases for
execution, press .
iRefer to the vehicle-specific documentation for the
A/C service parameters.
!Always pay attention to the vehicle-specific info be-
fore changing the quantity of oil and R134a.
3. Press  and then E.
The service parameters for the selected phases
are displayed.
4. Set the values of the service parameters.
5. Check the type of connection on the vehicle
A/C system.
!Do not use any tools to tighten the couplers.
6. Connect the appropriate coupler/s to the service
connection on the vehicle A/C system.
7. Press E.
The selected service phase starts. At the end of
the service, Hose Drain menu is displayed.
8. Turn the HP/LP quick couplers in the counterclock-
wise direction and disconnect from the service con-
nections on the vehicle A/C system.
9. Press E.
10. Press Eto start draining the refrigerant from the
hoses.
Once the refrigerant is drained, a summary
screen is displayed.
"The servicing of the vehicle A/C system is complete.

F 002 DG9 432 2014-12-19|Bosch Limited
Program description | ACS 255 | 17 en
6.8 Additional services
6.8.1 Refrigerant top up
If there is a decrease in the quantity of refrigerant in
the vehicle A/C system, an additional quantity can be
added.
Before doing a top up, the quantity of refrigerant al-
ready present in the car A/C system is not known. In
such a scenario, topping up might result in overcharging
of the refrigerant. A top up should be performed only
after ascertaining the quantity of refrigerant already
present in the car A/C system. Else, a complete A/C
service should be performed.
1. In the main menu, select "Vehicle A/C Service" >>
"Additional Services". Alternatively, press cand
select "Additional Services".
2. Select "Refrigerant Top Up" and press E.
3. Connect the LP coupler to the LP service connection
on the vehicle A/C system and press .
4. Start the vehicle and switch on the A/C. Press .
5. Enter the quantity of refrigerant to be topped up.
Press .
iThe valid top up quantity range is between 20 and
100 grams.
6. Press .
The refrigerant top up starts. At the end of the
service, Hose Drain menu is displayed.
7. Turn the HP/LP quick couplers in the counterclock-
wise direction and disconnect from the service con-
nections on the vehicle A/C system.
8. Press .
9. Press to start draining the refrigerant from the
hoses.
Once the refrigerant is drained, a summary screen
is displayed.
"You have successfully topped up the refrigerant in the
vehicle.
6.8.2 Hose drain
After every recharge / top up, some quantity of refriger-
ant is left in the hoses. It is necessary to drain the re-
frigerant from the hoses.
1. In the main menu, select " Vehicle A/C Service" >>
"Additional Services". Alternatively, press cand
select "Additional Services".
2. Select "Hose Drain" and press E.
The Hose Drain menu is displayed.
3. Turn the HP/LP quick couplers in the counterclock-
wise direction and disconnect from the service con-
nections on the vehicle A/C system.
4. Press .
5. Press to start draining the refrigerant from the
hoses.
Once the refrigerant is drained, a summary screen
is displayed.
"The hose drain is complete.
6.8.3 A/C performance test
The condition of the vehicle A/C system can be moni-
tored by checking the pressure and temperature at a
specific location as recommended by the vehicle manu-
facturer. The A/C performance can be done before or
after vehicle A/C service.
1. In the main menu, select " Vehicle A/C Service" >>
"Additional Services". Alternatively, press cand
select "Additional Services".
2. Select "A/C Performance Test".
3. Connect the HP and LP service hoses to the respec-
tive service connections on the vehicle A/C system.
Press .
4. Start the engine with the vehicle gear lever turned to
Neutral.
5. Switch on the vehicle A/C to Maximum (cooling to
maximum). Press .
6. Press .
7. Perform the A/C system test based on either of the
following as per the vehicle manufacturer’s recom-
mendation:
$Grill temperature
$HP and LP pressure gauge readings
8. After the A/C system test is complete, turn off the
engine and the vehicle A/C system.
9. Disconnect the HP and LP hoses from the service
connections of the vehicle A/C system. Press .
10. Press to start the hose drain.
"Upon completion of the hose drain, the A/C perfor-
mance test is complete.

F 002 DG9 432 2014-12-19| Bosch Limited
18 | ACS 255 | Maintenanceen
7. Maintenance
!Do not carry out any maintenance work that is not
specifically recommended in this section.
7.1 Spare and wearing parts
Description Order number
Filter dryer with set of inline filter
elements
F 002 DG1 4J9
Set of inline filter elements F 002 DG1 544
iContact your local Bosch dealer for ordering spare
and wearing parts.
7.2 Refilling the refrigerant tank
See chapter 4.5 for the procedure to fill the internal
refrigerant tank.
7.3 Service record
Use the "Service Record" option to view the following
information:
RReport of the last three vehicle A/C system services
RReport of the last self test
RLast five errors that occurred during vehicle A/C
service
To view the service record menu, execute the following
procedure:
¶In the main menu, select "ACS Maintenance" >>
"Service Record". Press E.
¶Alternatively, press c. Select "ACS Maintenance" >>
"Service Record"
"The Service Record menu is displayed.
7.3.1 Viewing the last three vehicle A/C service
reports
Use this option to view the last three vehicle A/C ser-
vice reports.
¶Select "Last 3 System Service Reports" and press
E.
7.3.2 Last self test
Use this option to view the last self test report.
1. To view the last self test report, select "Last Self
Test Report" and press E.
7.3.3 Last five errors during vehicle A/C service
Use this option to view the last five errors that occurred
during vehicle A/C service.
¶Select "Last 5 Errors" and press E.
iSee chapter 5 for the description of the error
messages.
7.4 Vacuum pump oil change
The vacuum pump oil needs to be changed after every
60 hours of operation. When it is time to change the
vacuum pump oil, the message Replace Vacuum
Pump Oil is displayed.
1. Perform hose drain (refer chapter 6.8.2).
2. Disconnect the HP and LP hoses from the respective
connectors.
3. Turn off the master switch.
4. Disconnect the power cable from the mains supply.
5. Disconnect the power cable from the power inlet.
6. Disconnect the fresh oil bottle and the used oil bottle.
7. Open the front panel.
Warning - Risk of burns!
The hot surface of the vacuum pump can
cause severe burns to the hands.
¶Allow the vacuum pump to cool before
commencing maintenance work
iUse a container to drain the vacuum pump oil.
8. Open the drain plug (Fig. 6, Pos. 3) and drain out
the vacuum pump oil.
9. Open the screw cap of the vacuum pump
(Fig. 6, Pos. 1).
!Ensure that the oil does not spill over when you fill
fresh oil.
10. Fill fresh vacuum pump oil. Observe the level
indicator (Fig. 6, Pos. 4) to check if the oil is suf-
ficiently filled.
11. Close the screw plug.
12. Close the front panel.
13. Attach the fresh oil bottle and the used oil bottle.
14. Connect the end connectors of the service
hoses (Fig. 7, Pos. 2) to the hose connections
(Fig. 7, Pos. 1). Observe the red / blue identifica-
tion stickers on the front panel before connecting
the hoses. Tighten the hose connections.
15. Connect the power cable to the power socket.
16. Connect the power cable to the mains supply.
17. Start the ACS 255.
18. In the main menu, select "ACS Maintenance" >>
"Maintenance". Press E.
19. Select "Reset Vacuum Pump" and press E.
20. Press to reset maintenance counter.
21. Press to confirm.
"You have successfully added oil to the vacuum pump
and reset the maintenance counter.

F 002 DG9 432 2014-12-19|Bosch Limited
Maintenance | ACS 255 | 19 en
7.5 Replacing the filter drier
The filter drier removes the moisture and suspended
particulate matter from the refrigerant. It is recom-
mended to change the filter drier after the specified
duration of usage. Reusing saturated filter driers may
result in reduced recycling capability of the ACS 255.
Consequently, the purity level of the refrigerant to be
charged to the vehicle A/C system also reduces.
iThe filter drier needs to be replaced after every
75 kg of refrigerant is recovered. When it is time to
replace the filter drier, the message "Filter Drier
Replacement Due" is displayed before starting
vehicle A/C service.
As soon as the warning message is displayed, contact
customer service for ordering a new filter drier.
iWhen inserting the new filter drier, ensure that it is
installed in the correct position.
1. Perform hose drain (see chapter 6.8.2).
2. Disconnect the power cable from the mains supply.
3. Disconnect the power cable from the power socket.
4. Disconnect the fresh oil bottle and the used oil
bottle.
5. Disconnect the HP and LP hoses from the respective
connectors.
6. Open the front panel.
1
2
3
4
5
459897_160Nkv
Fig. 9: Replacing the filter drier
1 Nut
2 Filter drier
3 Tie
4 Tie
5 Nut
7. Cut the cable ties (Fig. 9, Pos. 3, 4) that bind the
filter drier to the bracket of the ACS 255.
iUse a suitable spanner to unfasten or fasten the
nuts.
8. Hold the filter drier firmly and loosen the fastening
nuts (Fig. 9, Pos. 1, 5).
9. Detach the filter drier (Fig. 9, Pos. 2).
10. Connect the new filter drier. Ensure that the O-
rings are present at the mating part of the filter.
!Ensure that you tighten the fastening nut only after
ensuring that the threads of the filter drier are en-
gaged properly with the fitting.
!Ensure that you do not disturb the hose connections
or the electrical connections while replacing the
filter drier.
11. Tighten the fastening nuts.
12. Close the front panel.
13. Attach the fresh oil bottle and the used oil bottle.
14. Connect the end connectors of the service
hoses (Fig. 7, Pos. 2) to the hose connections
(Fig. 7, Pos. 1). Observe the red / blue identifica-
tion stickers on the front panel before connecting
the hoses. Tighten the hose connections.
15. Connect the power cable to the power inlet on the
ACS 255.
16. Connect the other end of the power cable to the
mains supply.
17. Power on the ACS 255.
18. In the main menu, select "ACS Maintenance" >>
"Maintenance".
19. Select "Reset Filter" and press .
20. Press to confirm.
"You have successfully replaced the filter drier and reset
the maintenance counter.
7.6 Replacing the inline filters
The inline filters have to be changed every time the fil-
ter drier is changed. The inline filters consist of a filter
insert (Fig. 10, Pos. 2) mounted inside the filter body.
1
2
3
4
459897_117Nkv
Fig. 10: Inline filter overview
1. Adapter for manifold
2. Filter insert
3. Adapter for hoses
4. O-ring

F 002 DG9 432 2014-12-19| Bosch Limited
20 | ACS 255 | Maintenanceen
During replacement, replace only the filter insert.
1. Perform hose drain (see chapter 6.8.2).
2. Turn off the master switch.
3. Disconnect the power cable from the mains supply.
4. Disconnect the hoses from the inline filters.
5. Grip the adapter (Fig. 10, Pos. 1) with a spanner.
Loosen the adapter for hoses (Fig. 10, Pos. 3) as
shown in fig. 11.
459897_45Nkv
Fig. 11: Removing the adapter for the hoses.
6. Remove the filter insert (Fig. 12, Pos. 1) from within
the adapter (Fig. 12, Pos. 2).
1
2
459897_43Nkv
Fig. 12: Removing the filter insert
1 Filter insert
2 Adapter for hoses
7. Place the new filter insert within the adapter.
iEnsure that the O-ring is in place and not damaged.
If damaged, change the O-ring.
8. Fasten the inline filters back to the adapter.
iEnsure that you do not damage the adapter for the
manifold while tightening the adapter for hoses. Use
tightening torque 9.5 N-m.
9. Connect the HP and LP hoses to the inline filters.
"You have successfully replaced the inline filters.
7.7 Self test
When the ACS 255 is powered on, a self test is initiated
automatically. It is also possible to trigger the self test
manually.
¶In the main menu, select "ACS Maintenance" >>
"Self Test'. Press E.
"The self test is initiated.
iIf the self test fails, contact customer service.
7.8 Firmware update
iUpdating the firmware does not affect the custom
database.
iBosch supplies USB disks for vehicle database up-
dates. Contact your local Bosch dealer or customer
service for further information.
1. Connect the power cable to the mains supply.
2. Turn on the master switch.
3. In the main menu, select "ACS Maintenance" >>
"Firmware Update". Press E.
iThe current version number is displayed. The mod-
ules for which an update is available is marked with
the symbol.
4. Plug in the USB to the USB port on the HMI module.
5. Follow the instructions on the screen to complete
the software update.
7.9 Resetting factory settings
Use this option to change the system default.
1. In the main menu, select "ACS Maintenance" >>
"Maintenance". Press E.
2. Select "Reset Factory Settings". Press E
3. Switch off and switch on.
"The settings have been reset to factory settings.