Valeo REVO-E Instruction manual

Rev. 06/2019
Id.No. 11123006A
REVO®-E Heat pump
Volvo
Workshop Manual
AIR CONDITIONING

1
REVO-E Heat pump Content
1 Introduction
1.1 Content and purpose 101
1.2 Validity of the workshop manual 101
1.3 Meaning of emphasis 101
1.4 Symbols 101
1.5 Additional documentation to be used 101
1.6 Safety information and condition 101
1.6.1 General safety information 102
1.6.2 Working with high-voltage air-conditioning systems 102
1.6.3 Working with refrigerants 102
1.6.4 Working with pressurized containers 103
1.6.5 Technical rules for pressurized gases (TRG) 103
1.6.6 Waste and residual materials 103
1.7 Suggestions for improvement and change 103
1.8 Abbreviations 104
2 Technical specifications
3 Description of assemblies and components
3.1 REVO-E HP versions on the Volvo 79xx Electric 301
3.2 Total overview of the design and components of the REVO-E heat pump 302
3.3 Overview of high-voltage cable harnesses / components (400V AC / 600V DC) 303
3.4 Cable harnesses overview (high-voltage / low-voltage) in the REVO-E HP 304
3.5 Design / task and function of the assemblies 305
4 Function and functional schematics of the REVO-E Heat pump
4.1 General function 401
4.2 Functional schematic of the REVO-E heat pump 402
4.3 Functional schematic of the REVO-E heat pump Volvo 7900 Electric 403
4.4 Work modes of the REVO-E heat pump in the Volvo 7900 Electric 404
4.4.1 Heating and Ventilation Mode (HV Mode) 405
4.4.2 Heating and Ventilation Mode Ready for cooling 406
4.4.3 Heating and Ventilation Mode Ready for Heat Pump Mode 407
4.4.4 Cooling Mode 408
4.4.5 Heat Pump Mode 410
4.4.6 Operating Mode De-Icing) (Version HP+ only) 412
4.4.7 Operating Mode Oil Recovering (Version HP+ only) 413
4.4.8 Reheat Mode 414
4.4.9 Waste Energy Mode 415
4.4.10 Gas Charging Mode 416
4.5 Refrigerant circuit function schematic of the heat pump 417
4.5.1 Refrigerant circuit function schematic of the heat pump in the Cooling Mode 418
4.5.2 Refrigerant circuit function schematic of the heat pump in the Heat Pump Mode 419
4.5.3 4-way reversing valve function schematic 420
4.5.4 Refrigerant circuit function schematic of the heat pump with hot gas de-icing (
11123865_ only) 422
5 Troubleshooting
5.1 General 501
5.2 Malfunctions in the air-conditioning circuit 501
5.2.1 Causes of malfunctions in the air-conditioning system 501
5.2.2 What to do for malfunctions in the refrigerant circuit 501
5.2.3 Why the desired conditions are not reached when testing pressure 501

2
REVO-E Heat pump Content
5.3 Malfunctions in the electrical system 501
5.4 Table of error codes 503
5.5 Error codes 504
5.6 Inspecting functionality of individual components 509
5.6.1 General visual inspection 509
5.7 Diagnosing the REVO-E units using the Diagnosis Control Test – DCT diagnostic software 509
5.8 Diagnosing the frequency converter 509
6 Wiring diagrams
6.1 Electrical fuses 601
6.2 Wiring diagram REVO-E HP (11120816*) 601
6.3 Wiring diagram REVO-E HP+ (11123865*) 608
6.4 Frequency converter - electrical connections 615
6.4.1 600V DC power supply including HVIL connector 615
6.4.2 400V AC voltage output 616
6.4.3 PE connection (potential equalizing) 616
6.5 Compressor - electrical connections 617
6.5.1 400V AC voltage supply 617
6.5.2 PE connection (potential equalizing) 617
7 Maintenance
7.1 Safety information 701
7.2 Versions of ADA 701
7.3 Maintenance and upkeep 701
7.4 Inspection and maintenance 701
7.4.1 Changing the fresh air filter 701
7.4.2 Changing the filter dryer 701
7.4.3 Inspecting the oil level of the compressor 702
7.4.4 Changing the compressor oil 702
8 Removal and installation of components (high-voltage system)
8.1 Safety information 801
8.2 Versions of ADA 801
8.3 Preparation/follow-up 801
8.3.1 High-voltage system 801
8.3.2 Refrigeration section 801
8.4 Frequency converter removal/ installation 802
8.4.1 Remove the frequency converter 802
8.3.2 Install the frequency converter 803
8.4 Refrigerant compressor removal/ installation 804
8.4.1 Remove the compressor 804
8.4.2 Comparing the old/new oil level 806
8.4.3 Install the compressor 806
8.5 600V DC/ 400V AC high-voltage cable removal/ installation 808
8.5.1 Remove the 600V AC cable 808
8.5.2 Install the 600V DC cable 808
8.5.3 Remove the 400V AC cable 808
8.5.4 Install the 400V AC cable 809
9 Removal and installation of components
9.1 Safety information 901
9.2 Versions of ADA 901
9.3 Preparation/follow-up 901
9.4 Condenser module removal/ installation 901

3
REVO-E Heat pump Content
9.4.1 Removal of the condenser module 901
9.3.2 Installation of the condenser module 902
9.4 Expansion valves removal/ installation 903
9.4.1 Positions of the expansion valves and the associated contact sensors 903
9.4.2 Remove an expansion valve 904
9.4.3 Install an expansion valve 904
9.5 Filter dryer removal/ installation 905
9.5.1 Remove the filter dryer 905
9.5.2 Install the filter dryer 905
9.6 Receiver removal/ installation 905
9.6.1 Remove the receiver 905
9.6.2 Install the receiver 905
9.7 Double radial blowers / axial fans removal/ installation 906
9.7.1 Remove a double radial blower 906
9.7.2 Install a double radial blower 906
9.7.3 Remove an axial fan 906
9.7.4 Install an axial fan 906
9.8 Recirculating air flap actuator motor removal/ installation 907
9.8.1 Remove the actuator motor 907
9.8.2 Install the actuator motor 907
9.9 Temperature sensor (duct / recirculating air suction) removal/ installation 907
9.9.1 Remove the duct temperature sensor (blow-out temperature) 907
9.9.2 Install the duct temperature sensor (blow-out temperature) 907
9.9.3 Remove the recirculating air suction temperature sensor (passenger compartment) 907
9.9.4 Install the recirculating air suction temperature sensor (passenger compartment) 907
9.10 Suction pressure sensor removal/ installation 908
9.10.1 Remove the suction pressure sensor 908
9.10.2 Install the suction pressure sensor 908
9.11 High-pressure sensor removal/ installation 908
9.11.1 Remove the high-pressure sensor 908
9.11.2 Install the high-pressure sensor 908
9.12 Pressure switch removal/ installation 909
9.12.1 Remove the pressure switch 909
9.12.2 Install the pressure switch 909
9.13 Compressor suction and pressure lines removal/ installation 909
9.13.1 Remove the pressure line 909
9.13.2 Install the pressure line 909
9.13.3 Remove the suction line 909
9.13.4 Install the suction line 909
9.14 Solenoid valve removal/ installation 910
9.14.1 Remove the coil 910
9.14.2 Install the coil 910
9.14.3 Remove the screw-in valve 910
9.14.4 Install the screw-in valve 910
Attachment A
Torque values/ seales A-1

101
REVO-E Heat pump 1 Introduction
1Introduction
1.1 Content and purpose
This workshop handbook is for repairs and maintenance
purposes of the rooftop system (subsequently referred to
as air-conditioning system) REVO-E.
Work on the air-conditioning system is only to be
conducted by personnel who are qualified pursuant
to DGUV Information 200-005 (old BGI 8686) or,
outside of the German market, by personnel who are
instructed/trained according to corresponding local
regulations.
The required qualifications differ depending on the
content and scope of the work on the air-conditioning
system. See point 1.6.1 below.
1.2 Validity of the workshop manual
This workshop manual is valid for all of the air-condi-
tioning systems listed on the cover page.
It may be subject to changes and addenda. The currently
valid version is binding. These are found on the Valeo
homepage in the Service / Downloads area.
1.3 Meaning of emphasis
In this handbook, the emphases of Warning!, Caution!,
ATTENTION: and NOTE: mean the following:
This heading is used when improperly following or
not following instructions or processes can lead to
serious injuries or fatal accidents.
This heading is used when improperly following or
not following instructions or processes can lead to
minor injuries.
ATTENTION:
Indicates procedures which may lead to material
damage.
NOTE:
Is used when something is to be emphasized.
1.4 Symbols
1.5 Additional documentation to be used
The use of additional servicing literature is required. This
is indicated in the workshop manual in the corresponding
location.
Use the following documents when operating and
servicing the air-conditioning system:
• Installation instructions for the REVO-E
• Evacuation and filling instructions for the REVO-E
• Maintenance and service plan for the REVO-E
• Spare parts list for the REVO-E Heat pump
• Technical information (TI)
This servicing literature is also available for download at
www.valeo-thermalbus.com/eu_en/Service/Downloads/
Air-Conditioning.
1.6 Safety information and condition
The air-conditioning system was designed and produced
according to EC directives. The system is safe to operate
if properly installed and used
in accordance with the installation, operation and
servicing instruction.
Nonobservance of the servicing literature listed under 1.5
and the instructions included within excludes Valeo from
liability.
Always observe the general accident prevention regula-
tions. The “general safety conditions” beyond the frame-
work of these regulations are listed below.
Potential risk to health
and life!
Warning!
Potential risk to health
and life!
Warning!
Hazardous to health!
Caution!
Symbol of tightening torque:
Used in graphics, indicates parts (e.g. lock
nuts, screws) that must be attached with a
certain tightening torque. The values of the
tightening torque are found in the torque table
in Attachment A and are binding.

102
REVO-E Heat pump 1 Introduction
1.6.1 General safety information
Required qualifications
To work on the refrigeration section of the air-condi-
tioning system, proof of both of the following qualifi-
cations is required:
– electrically qualified person (EQP)
EQP: Trained in non-electrical work on/near high-
voltage systems, knows the dangers, does not work
independently (supervision and controls), trained ac-
cording to DGUV 200-005 (old BGI 8686)
– Specialists trained inrefrigeration technology with cer-
tificate of competence pursuant to Directive (EC) no.
307/2008
To work on the high-voltage section of the air-condi-
tioning system, proof of both of the following qualifi-
cations is required:
– Electrician for HV systems in powered vehicles Voca-
tional education, job of repeating character, training
pursuant to DGUV 200-005 (old BGI 8686)
– Specialists trained inrefrigeration technology with cer-
tificate of competence pursuant to Directive (EC) no.
307/2008
NOTE:
The conditions of these rules are valid within the jurisdic-
tion of DGUV (German Social Accident Insurance) and
must be followed even in countries without special provi-
sions.
Know and follow the operating and servicing instruction
for the systems, tools and aids used as well as their
accompanying safety information from the manufacturer
when evacuating and filling the air-conditioning system.
Working on the bus roof
When working on the bus roof or hydraulic lifts, scaf-
folding, etc, take suitable measures to prevent falling.
1.6.2 Working with high-voltage air-
conditioning systems
Only conduct installation, maintenance and repair
work if the motor is still and the 24V DC power supply
as well as the high-voltage has been switched off.
Before starting work on the air-conditioning system,
ensure that the system is voltage-free and make sure
it remains so for the duration of the work.
In certain cases, the following safety rules must be
followed:
– make the system voltage-free
– ensure that the system cannot be reactivated
– check whether the system is voltage-free
– ground and short-circuit
– cover or block off neighboring voltage-carrying
parts
Electrical work may only commence if protective
measures against electrical shock, short-circuits and
electric arcs have been taken.
1.6.3 Working with refrigerants
ObserveEN378whenworkingoncoolingsystems.There
is an info data sheet or material sheet (available from
manufacturer) for each refrigerant as well as the general
information from professional organizations within the
chemical industry.
Certain conditions apply, that must be maintained, for the
safe and proper use of refrigerants:
– Wear protective eye wear when working with refriger-
ants. If a refrigerant gets into the eye, serious frostbite
damage may occur. Thoroughly rinse the eyes with
water immediately and seek medical attention.
– Wear protective gloves when working with refriger-
ants. Liquids refrigerant is not to come into contact
with the skin. The hands must be protected from frost-
bite (leaking R 134a condenses at -26.5°C) and from
erosion to the skin's protective layer (refrigerants dis-
solve fat)! If a refrigerant comes into contact with the
skin, thoroughly rinse the point of contact with water
immediately and seek medical attention.
High voltage!
Caution
Mortal danger!
Warning!
Danger of serious injury
or death by falling!
Warning!
High voltage!
Caution
Mortal danger!
Warning!
Hazardous to health!
Caution!

103
REVO-E Heat pump 1 Introduction
– There is a possible risk ofsuffocation if the refrigerant
leaks into the atmosphere. Refrigerants are heavier
than air. At and beyond a concentration of approx.
12% in the air, there will not be sufficient oxygen to
breathe. Loss ofconsciousness and increasedcardio-
vascular problems caused by stress and lack of
oxygen will result. This is a fatal hazard!
– It is forbidden to smoke when handling refrigerants. A
burning cigarette can break the refrigerant down. Poi-
sonous substances will form as a result.
– Before welding and soldering cooling systems, the
cooling system must be completely evacuated and
any residue removed by blowing in nitrogen. If
exposed to heat, refrigerants will release products of
decomposition that are not hazardous but can also
cause corrosion.
– Nonflammablerefrigerantsalsopose afire risk viathe
ignition ofdisplacedoil residueandinsulatingmaterial
as well as the oil mist caused by strong leakages.
1.6.4 Working with pressurized containers
– Ensure that the container does not fall over or roll
away
– Do not throw the container. If struck, the containers
may be so deformed that they rupture. Considerable
forces are let free if the heat exchanger is suddenly
struck and refrigerants leak out. The same applies if
cylinder valves break. Therefore, the cylinders are
only to be transported with protective cap.
– Refrigerant cylinders are not to be kept near heating
units. Higher temperatures mean higher pressures,
which may lead to the container exceeding its
maximumallowedpressure.The rulesforpressurized
containers stipulate that containers are not to be
warmed beyond 50 °C.
– Never warm refrigerant cylinders with an open flame.
The material may become damaged from the exces-
sive temperature, resulting in decomposition of the re-
frigerant.
– Close empty containers to prevent the entry of mois-
ture.
– Never overfill refrigerant cylinders, since an increase
in temperature can lead to enormous pressures.
1.6.5 Technical rules for pressurized gases
(TRG)
The applicable rules for the manufacturer and workshop
are listed in the Technical Rules for Pressurized Gases
(TRG).Personnelwhoconductedmaintenanceandrepair
work on the air-conditioning system must know and follow
these rules.
1.6.6 Waste and residual materials
The valid legal conditions and regulations, that concern
waste disposal as well as how to process residual mate-
rial, must be followed.
Disposing of refrigerant and refrigerator oil
Therefrigerants tobe disposed ofare tobeplaced intothe
labeled recycling containers, taking into consideration the
present fill level.
Used refrigerator oils from systems with halogenated
hydrocarbons must be disposed of as special waste. It is
forbidden to mix these with other oils or substances.
Follow country-specific guidelines for proper storage and
disposal.
1.7 Suggestions for improvement and
change
Please refer any complaints, suggestions for improve-
ment or change for this manual to:
[e-mail]
Potential risk to health
and life!
Warning!
Potential risk to health
and life!
Warning!

104
REVO-E Heat pump 1 Introduction
1.8 Abbreviations
Abbreviations DE EN Description
REVO-E HP - ident no. 11120816_
- installed on Volvo E Bus
1st Generation
- lower operating limit
HP ≥3°C
REVO-E HP+- ident no. 11123865_
- installed on Volvo E Bus
2nd Generation
- llower operating limit
HP ≥-5°C
AC Klimaanlage Air Condition air conditioning only
ADA Aufdachanlage Roof Top Unit
BEA (el.) Body Electrical Architecture electronic regulations of the pas-
senger compartment
DCT Diagnose Control Test Diagnosis Control Test previously Spheros Control Test
–SCT
EU6 Euro 6 Euro 6 Europe variant
GH Global Hybrid global chassis application
HGA Heißgasabtauung Hot Gas Deicing
HV Hochvolt High Voltage
HVAC Heizen/ Lüften/ Klima Heating/ Ventilation/ Air-
Conditioning
HVIL High Voltage Interlock Loop High voltage interlock loop
i.O. / OK in Ordnung in working order
n.i.O. / NOK nicht in Ordnung not in working order
PE Potentialausgleich Potential Equalizing safety earthing
PTC positiver Temperatur-
koeffizient Positive Temperature Coefficient
SC600 ECU REVO-E AC electronic control unit
REVO-E AC (replaced by
SC610)
SC610 ECU REVO-E AC electronic control unit
REVO-E AC (replaced by
SC610)
SC620 ECU REVO-E WP ECU REVO-E HP electronic control unit
REVO-E WP
V AC Wechselspannung Volts Alternating Current
V DC Gleichspannung Volts Direct Current
HP Wärmepumpe Heat Pump ADA with heat pump function

201
REVO-E Heat pump 2 Technical specifications
2 Technical specifications
The technical specifications, provided that there are no
limit values given, comply withthe standard tolerances for
air-conditioning systems of ±10% for an ambient temper-
ature of +20° C and nominal voltage.
Table 201 Technical specifications
1) Tambient = 35 °C, Tcabin = 40 °C
2) Tambient = 5 °C , Tcabin = 20 °C
3) Version installed two times in articulated vehicle
REVO-E heat pump REVO-E HP+ REVO-E HP
11123865_311120816_
Application Volvo E-Bus 2nd
Generation
(from 2018)
Volvo E-Bus 1st
Generation
(till 2018)
Operating range heat pump [°C] ≥-5 ≥3
Cooling capacity [kW] 125
Heating capacity in heat-pump-mode [kW] 216
Heating capacity coolant circuit [kW] 40
Air volume [m³/h] 6960
Current consumption [A]
(24 V DC) maximum (all 100 %) 85
nominal (condenser 80%, evaporator 70%) 55
regulated
(the temperature in the passenger compartment is at set
point)
11
Current consumption [A]
(600 V DC) maximum (compressor speed at 50Hz) 22
regulated
(the temperature in the passenger compartment is at set
point 25°C - ambient temperature 35 °C, reduced com-
pressor speed)
9
Weight [kg] 272
Dimensions (length x wide x height) [mm] 2802x2091x406
Operation voltage range [V DC] 450-750
Refrigerant R134A
Filling capacity w/o front box[kg] 5
Filling capacity with front box [kg] 5.5

301
REVO-E Heat pump 3 Assemblies and components
3 Description of assemblies and components
3.1 REVO-E HP versions on the Volvo 79xx Electric
Abb. 1 REVO-E HP Installation variants
REVO-E HP/HP+(Zone 1)
For connection to front box
REVO-E HP
(11120816_) 1st generation - on solobuses
REVO-E HP+
(11123865_) 2nd generation - on solobuses und
articulated variants
ADA on solobus
REVO-E HP+(Zone 1) REVO-E HP+(Zone 2)
ADA on articulated system
air conditioning only
11120816_ / 11123865_
11123865_ 11123865_

302
REVO-E Heat pump 3 Assemblies and components
3.2 Total overview of the design and components of the REVO-E heat pump
Fig. 2 REVO-E Heat pump total overview
Direction of travel
373839
40
41
42
43
1
14
23 468 97 10
13
511
12
15
16
17
18
19
20
21
22
23
24
3435
26
25
27
282930313336
1) Figure shows 11123865_
2) Red marked components in 11123865_ only
44
46
45
1 Double radial blower
2 Right-hand forward safety lift
point of the unit
3 Blow-out temperature sensor
4 Temperature sensor, passenger
compartment (hidden)
5 Air filter
6 Electrical interface 24V
7 Bleeding port, heating element
NW6
8 Water feed flow NW20
9 Water return NW20
10 Filter Dryer
11 Sight glass
12 Solenoid valve
13 Expansion valve cooling circuit
14 Right-hand rear safety lift point
of the unit
15 Refrigerant charging valve,
suction side
16 Expansion valve heating circuit
heat pump
17 Safety valve, 30bar
18 Bracket, refrigerant compressor
19 Refrigerant collector
20 Refrigerant compressor
21
Refrigerant charging valve,
discharge side
22 Suction pressure sensor
(hidden)
23 Left-hand rear safety lift point of
the unit
24 Expansion valve cooling circuit
25 4-way reversing valve
26 Coil 4-way reversing valve
27 High pressure sensor
28 Refrigerant connection, suction
side, defroster
29 Refrigerant connection, dischar-
ge side, defroster
30 Protective Earth (PE), high
voltage components
31 Bleeding port, heating element
NW6
32 Low pressure safety switch *
33 High pressure safety switch
34 Air filter
35 Inner heat exchanger
36 Left-handforwardsafetyliftpoint
of the unit
37 Electrical interface 600V DC
38 Flap actuator (hidden)
39 Axial fan
40 Outer heat exchanger
41 Fan module
42 Frequency inverter
43 Flap actuator (hidden)
44 Solenoid valve hot gas deicing
45 Muffler
46 diagnostics port frequency inver-
ter
* not in 11123865_

303
REVO-E Heat pump 3 Assemblies and components
3.3 Overview of high-voltage cable harnesses / components (400V AC / 600V DC)
Fig. 3 Overview of high-voltage cable harnesses / components (400V AC / 600V DC)
1 - High-voltage power supply of the frequency converter 600V DC
2 - High-voltage power supply of the compressor 3x 400V AC
1
2
Frequency converter Compressor with 3x 400V AC e-motor
600V DC -> 3x400V AC

304
REVO-E Heat pump 3 Assemblies and components
3.4 Cable harnesses overview (high-voltage / low-voltage) in the REVO-E HP
Fig. 4 Cable harnesses overview (high-voltage / low-voltage) in the REVO-E HP
Item Description Remarks
1 wiring harness incl. connection board 24V interface ADA
2 temperature sensor blow out temperature
3 temperature sensor passenger compartment temperature
4 wiring harness temperature sensor passenger compartment
5 wiring harness axial fan, 4-way reversing valve
6 solenoid valve hot gas deicing in 11123865_ only
7 wiring harness kit, 400V AC frequency converter
8 PE connection compressor
9 compressor
10 suction pressure sensor
11 wiring harness double radial fan
12 high pressure sensor
13a high pressure safety switch
13b low pressure safety switch not in 11123865_
14 wiring harness, 600V DC HV interface, vehicle - frequency converter
15 frequency converter 600V DC -> 3x400V AC
16 diagnostic cable frequency converter
17 wiring harness control unit SC620 to ADA
18 SC620 control device installed in Volvo E bus
18
14
4321
5
6
7
17
8
9
10
15
11
12
13a/13b
16

305
REVO-E Heat pump 3 Assemblies and components
3.5 Design / task and function of
the assemblies
The REVO-E heat pump features an outer and an inner
heat exchanger.
They consist of aluminum tubes and aluminum fins which
are jointly connected and form a large heat exchanger
surface.
Outer heat exchanger
In the air-conditioning mode it works as condenser. If the
unit is in the heat pump mode, it is working as evaporator.
Inner heat exchanger
In the air-conditioning mode they work as evaporator. If
the unit is in the heat pump mode, they are working as
condenser.
Condenser function
It cools the hot refrigerant gas in such a way that it lique-
fies, subcools and transfers the condensation heat to the
external air flowing through it via the fins.
Evaporator function
Theevaporatorabsorbstheheatfromitsenvironmentand
delivers it to the refrigerant. In this process the evapora-
tion temperature must be lower than the ambient temper-
ature.
By the simultaneous suction action of the refrigerant
compressor and the constriction of the expansion
member, the desired evaporation temperature can be
achieved in a targeted manner.
The heat flowing because of the temperature difference
between the evaporator and the environment causes the
refrigerant liquid fed in by the expansion element to evap-
orate (evaporation zone) and to overheat (overheating
zone) in the evaporator.
Compressor (HGX34P/315-2 A)
This semi-hermetic, 4 cyl. reciprocating compressor is
drivenbya2pole,asynchronous motorintegratedintothe
housing. It is flushed / cooled by R134a, a gaseous refrig-
erant, and an integrated PTC element monitors the
temperaturelevel.Signals areevaluatedby thefrequency
converter. The frequency converter also provides power
and controls the speed.
The duty of the compressor is to condense vaporous
refrigerant from low pressure to a higher pressure. To do
so, it must ensure the necessary discharge (refrigerant
flow) required for cooling.
The compressor is integrated into the air-conditioning
system. The compressor with patented vibration decou-
pling design is created using a special absorption foam.
The compressor is embedded and fixed in this foam.
Receiver
The receiver is a compensating/ storage tank which
balances out changes in the refrigerant circuit.
Dryer
Theinteriorof thedryercontainsagranulatethat removes
small amounts of water from the refrigerant and chemi-
cally binds to it.
The dryer also filters contaminates from the refrigerant
that might lead to malfunctions.
A further expansion valve for heat pump operation is
installed in the heat pump.
Thermostatic expansion valve
The thermostatic expansion valve with external pressure
equalization regulates the refrigerant flow to the
compressor, depending on the refrigerant needs or the
condenser temperature. The thermostatic expansion
valve is the control element between the high and low
pressure sections of the refrigerant circuit.
Pressure switch
The high and low pressure switches are installed on the
compressor and are a key component of the safety chain
of the air-conditioning system.
High pressure switch
– Monitors the pressure level in the high-pressure area
of the refrigerant circuit
– Deactivates the air-conditioning system if pressure is
too high (e.g. too much refrigerant)
Low pressure switch
– Monitors the pressure level in the low-pressure area
of the refrigerant circuit
– Deactivates the air-conditioning system if pressure is
too low (e.g. too little refrigerant)
– The low pressure switch is not installed in the
11123865_ and is replaced by an SW algorithm.
Switch point
1) not in 11123865_
Axial fans
The three axial fans are driven by EC motors.
If Cooling Mode is activated, the fans are continuously
controlled depending on the load (refrigerant pressure)
via the PWM, and provide the outer heat exchanger with
sufficient fresh air.
Switch point High pressure
switch Low pressure
switch 1
On 19 ± 1.5 bar
(relative) 1.8 ± 0.3 bar (relative)
Off 24 ± 1.0 bar
(relative) 0.3 ± 0.3 bar (relative)

306
REVO-E Heat pump 3 Assemblies and components
Double radial blowers
The six double radial blowers are driven by EC motors.
The blowers move recirculated/ fresh air through the heat
inner exchanger and blow it at the right temperature
(depending on the mode) into the air ducts of the vehicle.
Speed controls are continuous (PWM); e.g. speed is
reduced when the desired passenger compartment
temperature has been reached. This reduces energy
needs and helps to stabilize the passenger cabin temper-
ature.
Frequency converter
This component is supplied via the 600V DC electrical
system of the vehicle and provides 400V AC for the three-
phaseACmotorof thecompressor.Dependingon system
requirements, the compressor speed is set between
10Hz-50Hz.
The frequency converter is placed onto an adapter plate
(Fig. 803), which makes it easy to remove / install.
4-Way reversing valve
Depending on the position, the 4-way reversing valve acti-
vates the air conditioning mode or the heat pump mode.
In zero position, the air conditioning mode is active.
Solenoid valve hot gas deicing REVO-E HP +
The hot gas deicing solenoid valve is installed on the
11123865_ ONLY. It is activated to defrost the outer heat
exchanger with hot gas from the refrigerant circuit.
Sensors
Suction pressure
The suction pressure sensor determines the pressure
level in the permanent low-pressure area. The system
attemptsto manage the suction pressure between 3.0 bar
and 3.7 bar (absolute).
Central parameters for:
– climate/ heat pump control
– recognizing icing
– recognizing low pressure
High pressure
Thehighpressuresensordeterminesthepressurelevelin
the permanent high-pressure area.
In heat pump mode, the target pressure is approx. 12 bar
depending on the ambient temperature.
Passenger compartment temperature
This sensor measures the air temperature of the
passenger cabin around the intake area of the recircu-
lating air (Fig. 908).
Air duct temperature (blow-out temperature)
This sensor measures the air intake temperature of the
air-conditioning system at the first double radial blower,
front right (Fig. 908).
Monitoring the temperature of the e-motor of the
compressor
A PTC element monitors the temperature of the
compressor e-motor. The frequency converter evaluates
the signal without directly influencing the air-conditioning
control.
R25 ≤300 Ω
If the e-motor overheats, the frequency converter stops
the compressor immediately (safety function).
Air valves
Regulate the intake of fresh air or use of recirculated air
from the passenger cabin. The BEA body sends the posi-
tional signals “open / closed” via CAN to the SC620 in all
operating modes (except for Gas Charging mode). If both
signals are active, the valves will move to the Recircu-
lating position. Intermediate positions (air mixing) are not
provided in this vehicle.
SC620
This control unit is used as the control device in the Volvo
7900 Electro system (display / keyboard inactive).
HVAC demands are only managed by the BEA body, the
SC620 works as a “slave system” and controls the func-
tions of the ADA.
Two LEDs become active when the system is turned on
(permanent & blinking).

401
REVO-E Heat pump 4 Function and functional schematics
4 Function and functional
schematics of the REVO-E Heat pump
4.1 General function
The fully electric rooftop air-conditioning system (in the
following referred to as ADA) REVO-E for hybrid, electric
and trolley buses is a proven system, especially with its
intelligent energy management, meaning cooling is
provided as needed depending on existing power, and
with the special way its compressor has been installed.
The electric compressor is located on the roof in an
exceptionally compact manner, and not on the rear of the
vehicle as in previous versions. This has, in the purest
sense of the word, obvious advantages and makes the
system closed by integrating all of the components
carrying refrigerant, an efficient, tight and almost mainte-
nance free design (solo design without front box connec-
tion).
The REVO-E as heat pump
The REVO-E air-conditioning system is the basis for the
REVO-E heat pump.
The refrigeration cycle of the REVO-E air-conditioning
system has been modified in such a way that it can also
represent the functionality of a heat pump in addition to
the air-conditioning operation. The basic principle is
based on the reversal of the refrigeration cycle.
Regulation and control in the air-conditioning mode corre-
spondtothe REVO-Eair-conditioningsystem.Detailscan
be found in the Workshop Manual REVO-E.
Explanations in the following chapters refer largely to the
new functions of the heat pump.
The intelligent controller logic of the SC620 controls
furthertheentiresystem.Itcommunicateswiththevehicle
via CAN bus.
The climate control works identical as in the REVO-E
air-conditioning system (see Workshop Manual REVO-E).
The two variants of the REVO-E HP are listed in the Table
201.
Both systems differ only slightly. With the additional func-
tion "hot gas de-icing", the REVO-E HP + is able to heat
the passenger compartment in heat pump mode at signif-
icantly lower temperatures (≥-5 ° C). This is realized with
adapted software and additional components in the refrig-
eration cycle.
Functionality of the REVO-E Heat pump in the vehicle
line of the Volvo 7900 Electric
The HVAC control system of the vehicle is responsible for
regulating the Heating, Ventilation and Cooling modes in
the Volvo E Bus. The REVO-E system is operated only as
a “slave” system and only follows the vehicles require-
ments.
If the ADA is activated by switching on the vehicles elec-
trical network. all of the system’s sensor values are auto-
matically verified for plausibility and the system will be set
to“StandbyMode”.Varioussensorvaluesareused asthe
basis for calculating the bus-side requirements, including
those from the passenger cabin sensors of the ADA.
These requirements are sent via CAN bus over the Dbus
to the SC620 as needed.
The SC620 implements these requirements (mode /
blower speed, etc.).
The REVO-E will turn off if there are any limitations in the
temperature / high-voltage supply, etc.

402
REVO-E Heat pump 4 Function and functional schematics
4.2 Functional schematic of the REVO-E heat pump
Tasks of the SC620
– Implementing climatic and heat pump requirements
– Turning off high-voltage components in case of error
(HVIL)
– Component protection of the climate unit if overloaded
Required to start the system:
– Power supply clamp 30 (main switch of battery)
– Ignition on (clamp 15)
– CAN communication between vehicle and SC620 ac-
tivated - approval for system start shared
– High voltage to the frequency converter, that means
high voltage system active
– Approval (D_AuxiliaryPowerEnable) and supply
Fig. 401 Functional schematic of the REVO-E
Analog input
HVIL 1 voltage
Analog input
HVIL 2 voltage CAN interface
vehicle
SC620
Sensor
blow-out
temperature Sensor
pass. comp.
temperature
Double radial blower
Speed
Compressor
Fresh air
flaps actuator
Double radial blower
Axial fans
Frequency
converter
Fresh air
flaps
actuator
active
Compressor activate
45
12
3
6
7
NOTE:
Detailsaboutthepositionscanbefoundin
the overview Fig. 2 in Chapter 3 of the
workshop manual.
1 Solenoid valve
2 Solenoid valve HGA / actu-
ator (in 11123865_only)
3 Suction pressure sensor
4 High pressure safety switch
5 Low pressure safety switch
(not in 11123865_)
6 4-way reversing valve
7 High pressure sensor
24V
4-way reversing valve works as actuator

403
REVO-E Heat pump 4 Function and functional schematics
4.3 Functional schematic of the REVO-E heat pump Volvo 7900 Electric
On single buses, the ADA and SC620 are connected to
one another using a Valeo cable harness.
The HVAC control system of the BEA body system is res-
ponsible for regulating the Heating, Ventilation, Cooling
and Heat pump modes in the Volvo e-bus.
The REVO-E system therefore behaves only as a “slave”
system and implements the particular requirements.
In Heating / Ventilation or Reheat Mode, the vehicle
controller gives the speed of the double radial blowers.
In Cooling, Waste Energy or Gas Charging Mode, the
double radial blowers are controlled by the SC620.
.
Fig. 402 Functional schematic of the REVO-E, internal
Analog input
HVIL 1 voltage
Analog input
HVIL 2 voltage CAN interface
vehicle
SC620
Sensor
blow-out
temperature Sensor
pass. comp.
temperature
Double radial blower
Speed
Compressor
Fresh air
flaps actuator
Double radial blower
Axial fans
Frequency
converter
Fresh air
flaps
actuator
active
Compressor activate
45
12
3
6
7
1 Solenoid valve
2 Solenoid valve HGA / actu-
ator (in 11123865_only)
3 Suction pressure sensor
4 High pressure safety switch
5 Low pressure safety switch
(not in 11123865_)
6 4-way reversing valve
7 High pressure sensor
24V
D-Bus Volvo
4-way reversing valve works as actuator

404
REVO-E Heat pump 4 Function and functional schematics
4.4 Work modes of the REVO-E heat
pump in the Volvo 7900 Electric
There are 9 different operating modes.
The well-known 6 operating modes of the REVO-E air-
conditioning system (see WM REVO-E) are extended by
three working modes.
Inthefollowingexplanations,onlythenew workingmodes
are considered.
Choosing or switching between modes occurs according
to defined criteria of the BEA body climate control system.
1. Heating/ Ventilation Mode
2. Heating/ Ventilation Mode Ready for Cooling
3. Heating/ Ventilation Mode Ready for Heat Pump *
4. Cooling Mode
5. Heat Pump Mode *
6. De-Icing Mode ** (11123865_only)
7. Reheat Mode
8. Waste Energy Mode
9. Gas Charging Mode
*) new mode for heat pump
**) in 11123865_only
This is a list of priorities in case several modes are simul-
taneously required by the BEA body system. The SC620
must employ the mode with the highest priority.
Operating mode De-Icing (in 11123865_ only)
This mode is activated by the SC620 depending on the
state of icing. The BEA body control is only informed
about the mode. In this mode, the heat pump function is
disabled.
General operating mode conditions:
- mode required by BEA body (e.g. Cooling Mode to
reduce the temperature in passenger compartment or
Heat Pump Mode to increase the temperature in
passenger compartment)
- general system conditions (e.g. external temperatures
/ status of 600V DC system)
- operating mode de-icing not activated
Depending on the mode, the SC620 or BEA body system
will control the actuators.

405
REVO-E Heat pump 4 Function and functional schematics
4.4.1 Heating and Ventilation Mode (HV Mode)
Requirements:
– Clamp 30 active
– HV Mode required by BEA body
Both modes are required directly by the BEA body.
CAN messages from the BEA body to SC620 for defined
speed of double radial blowers and position of air flaps
(fresh air / recirculating air).
Water valves are controlled by the BEA body directly.
Fig. 403 Heating and Ventilation Mode (HV Mode)
Double radial blower
Double radial blower
Fresh air
flaps
Sensor
pass. comp.
temperature
Sensor
blow-out
temperature
I/O-A module
Vehicle
Requirement
open / close
Heating valve
actuator
Fresh air
flaps
actuator
Analog input
HVIL 1 voltage
Analog input
HVIL 2 voltage CAN interface
vehicle
SC620
45
12
3
6
7
24V
for hot water
heat exchanger
ADA
1 Solenoid valve
2 Solenoid valve HGA / actu-
ator (in 11123865_only)
3 Suction pressure sensor
4 High pressure safety switch
5 Low pressure safety switch
(not in 11123865_)
6 4-way reversing valve
7 High pressure sensor