Webasto Air Top Evo 40 User manual

Air Heater
Air Top Evo 40/55
Air Top Evo 40 B / Air Top Evo 55 B (Benzin)
Air Top Evo 40 D / Air Top Evo 55 D (Diesel)
Service Manual

Improper installation or repair of Webasto heating and cooling systems can cause fire or the leakage of
deadly carbon monoxide leading to serious injury or death.
To install and repair Webasto heating and cooling systems you need to have completed a Webasto training
course and have the appropriate technical documentation, special tools and special equipment.
Only genuine Webasto parts may be used. See also Webasto air and water heaters accessories catalogue.
Webasto heating and cooling systems require qualified and/or professional installation and repair
technicians. Warranty shall be void if not installed by a certified or trained installer/repair technician who
has successfully completed the factory training course for installation and repair of Webasto heating and
cooling systems, and has been provided with the technical information, tools and equipment required to
properly complete the necessary installation/repairs.
ALWAYS carefully follow Webasto installation and repair instructions and heed all WARNINGS.
Webasto rejects any liability for problems and damage caused by the system being installed by untrained
personnel.
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Air Top Evo 40 / Air Top Evo 55 Service Manual

Table of Contents
1. Introduction..................................................................................................................................................................... 7
1.1 Contents and Purpose .............................................................................................................................................. 7
1.1.1 Use of air heaters.............................................................................................................................................. 7
1.2 Meaning of Signal Words ......................................................................................................................................... 7
1.3 Additional Documentation to be used ...................................................................................................................... 7
1.4 Statutory Regulations and Safety Instructions ........................................................................................................... 7
1.4.1 Statutory Regulations Governing Installation..................................................................................................... 7
1.4.2 General Safety Precautions ............................................................................................................................... 8
2. General Description ....................................................................................................................................................... 10
2.1 Drive Unit .............................................................................................................................................................. 11
2.2 Heat Exchanger ..................................................................................................................................................... 12
2.3 Evaporator Mount with Combustion Pipe ............................................................................................................... 12
2.4 Glow Plug............................................................................................................................................................... 13
2.5 Exhaust Temperature Sensor................................................................................................................................... 13
2.6 Overheat Temperature Sensor ................................................................................................................................ 14
2.7 Control Unit ........................................................................................................................................................... 14
2.8 Fuel Pump .............................................................................................................................................................. 15
3. Function Description ...................................................................................................................................................... 15
3.1 Control Element ..................................................................................................................................................... 15
3.2 Switching On.......................................................................................................................................................... 16
3.3 Heating Mode ........................................................................................................................................................ 16
3.4 Control Mode......................................................................................................................................................... 17
3.5 Control Break ......................................................................................................................................................... 17
3.6 Switching Off ......................................................................................................................................................... 17
3.7 Functions of Air Top Evo System ............................................................................................................................. 17
3.7.1 Installation/Commissioning ............................................................................................................................. 17
3.8 Fault Switch-Off...................................................................................................................................................... 18
3.8.1 Error Monitoring............................................................................................................................................. 18
3.8.2 Reset a Fault Switch-Off.................................................................................................................................. 18
4.0 Technical Data............................................................................................................................................................ 19
5.0 Troubleshooting ......................................................................................................................................................... 21
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Air Top Evo 40 / Air Top Evo 55 Service Manual

5.1 General Information ............................................................................................................................................... 21
5.2 General Error Symptoms......................................................................................................................................... 21
5.3 Error Symptoms During Function ............................................................................................................................ 22
5.4 Fault code displayed in control element .................................................................................................................. 22
5.5 Maintenance display in control element.................................................................................................................. 24
6.0 Functional Checks....................................................................................................................................................... 24
6.1 General Information ............................................................................................................................................... 24
6.2 Required test and measuring equipment................................................................................................................. 24
6.3 Settings .................................................................................................................................................................. 25
6.3.1 Factory Settings .............................................................................................................................................. 25
6.3.2 Adjusting CO2content .......................................................................................................................................... 26
6.4 Tests of Individual Components .............................................................................................................................. 26
6.4.1 Burner Component Assembly ......................................................................................................................... 27
6.4.2 Resistance Test of Exhaust Temperature Sensor .............................................................................................. 28
6.4.3 Heating Air Fan Component ........................................................................................................................... 29
6.4.4 Glow Plug Component ................................................................................................................................... 30
6.4.5 Drive Unit Component.................................................................................................................................... 31
6.4.6 Overheat Temperature Sensor Component ..................................................................................................... 32
6.4.7 Control Unit Component................................................................................................................................ 34
6.4.8 Heater Component......................................................................................................................................... 35
7.0 Wiring Diagrams......................................................................................................................................................... 37
7.1 General Information ............................................................................................................................................... 37
7.2 Legend for Wiring Diagrams ................................................................................................................................... 42
8.0 Service Work .............................................................................................................................................................. 45
8.1 General Information ............................................................................................................................................... 45
8.2 Work on Heater...................................................................................................................................................... 45
8.3 Work on Vehicle ..................................................................................................................................................... 45
8.4 Heater test operation.............................................................................................................................................. 45
8.5 Servicing work ........................................................................................................................................................ 45
8.6 Visual inspections and installation instructions ........................................................................................................ 46
8.6.1 Cold and hot air system ........................................................................................................................................ 46
8.6.2 Fuel System........................................................................................................................................................... 47
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Air Top Evo 40 / Air Top Evo 55 Service Manual

8.6.3 Combustion air system ......................................................................................................................................... 48
8.6.4 Exhaust system ..................................................................................................................................................... 48
8.6.5 Combustion air inlet and exhaust lines.................................................................................................................. 49
8.6.6 Electrical connections............................................................................................................................................ 50
8.7 Removal and Installation......................................................................................................................................... 53
8.7.1 Heater, Removal and Installation..................................................................................................................... 53
8.8 Start-up........................................................................................................................................................................ 53
9.0 Repair......................................................................................................................................................................... 53
9.1 General information ............................................................................................................................................... 53
9.1.1 Measures on dismantled components............................................................................................................. 53
9.1.2 Carrying out modifications ............................................................................................................................. 54
9.2 Dismantling and assembling......................................................................................................................................... 55
9.2.2 Fit the housing parts....................................................................................................................................... 55
9.2.3 Replacing control unit..................................................................................................................................... 56
9.2.4 Replacing Overheat Temperature Sensor......................................................................................................... 57
9.2.5 Replacing heating air fan ................................................................................................................................ 57
9.2.6 Replacing drive unit ........................................................................................................................................ 57
9.2.7 Replacing exhaust temperature sensor.................................................................................................................. 58
9.2.8 Replacing evaporator mount and glow plug ......................................................................................................... 60
9.2.9 Change the combustion chamber and the heat exchanger ................................................................................... 61
10.0 Packaging, storage and shipping ................................................................................................................................ 62
10.1 General information ............................................................................................................................................... 62
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Air Top Evo 40 / Air Top Evo 55 Service Manual

Table of Figures
Figure 1: Air Top Evo 40/55 Air Heater .................................................................................................................................. 11
Figure 2: Air Top Evo 40/55 .................................................................................................................................................. 11
Figure 3: Drive Unit................................................................................................................................................................ 11
Figure 4: Heat Exchanger....................................................................................................................................................... 12
Figure 5: Evaporator Mount with........................................................................................................................................... 12
Figure 6: Evaporator Mount with........................................................................................................................................... 12
Figure 7: Glow Plug ............................................................................................................................................................... 13
Figure 8: Exhaust Temperature Sensor ................................................................................................................................... 13
Figure 9: Overheat Temperature Sensor................................................................................................................................. 14
Figure 10: Control Unit.......................................................................................................................................................... 14
Figure 11: Fuel Pump............................................................................................................................................................. 15
Figure 12: Components Required .......................................................................................................................................... 25
Figure 13: Characteristic resistance value of a PT 2000 Overheat Temperature Sensor in the temperature range 10 °C to 30 °C
.............................................................................................................................................................................................. 32
Figure 14: Connector Assignment on Control Unit ................................................................................................................ 38
Figure 15: Wiring Diagram for Air Top Evo 40 / 55, 12V / 24V with rheostat .......................................................................... 39
Figure 16: Wiring Diagram for Air Top Evo 40 /55, 12V/24V with MultiControl (MC04) control element ............................... 40
Figure 17: Wiring diagram for Air Top Evo 40 / 55, 12V / 24V with Smartemp....................................................................... 41
Figure 18: Connection Diagram for Air Top 40 / 55 with Air Top Evo MultiControl (MC04) control element......................... 42
Figure 19: Installation Position of Fuel Pump DP 42................................................................................................................. 47
Figure 20: Fuel Filter, installation position and flow direction ................................................................................................. 48
Figure 21: Permissible installation position of.......................................................................................................................... 49
Figure 22: Permissible installation position of exhaust pipe end .............................................................................................. 50
Figure 23: Remove the fastening plate on the fuse holder ...................................................................................................... 50
Figure 24: Fuse Holder, installation position............................................................................................................................ 50
Figure 25: Rheostat ................................................................................................................................................................ 51
Figure 26: Disconnect the Plug ............................................................................................................................................... 51
Figure 27: Installation example for heater in recirculated air mode.......................................................................................... 52
Figure 28: External room temperature sensor ......................................................................................................................... 55
Figure 29: Removing/fitting housing parts .............................................................................................................................. 56
Figure 30: Replace control unit, Overheat Temperature Sensor, .............................................................................................. 58
Figure 31: Cable for exhaust temperature sensor.................................................................................................................... 59
Figure 32: Sealing surface of exhaust temperature sensor....................................................................................................... 59
Figure 33: Top view of heat exchanger ................................................................................................................................... 60
Figure 34: Replacing evaporator mount, glow plug,................................................................................................................ 62
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Air Top Evo 40 / Air Top Evo 55 Service Manual

1. Introduction
1.1 Contents and Purpose
This workshop manual is used to support instructed personnel when repairing the Air Top Evo 40 / Air Top Evo 55 benzin
or diesel air heaters.
1.1.1 Use of air heaters
The Webasto Air Top Evo 40 / Air Top Evo 55 air heaters are used:
–To heat cabins, boats, trucks, minibuses, vans, ambulances and motorhomes
–To defrost vehicle windows
–To heat cargo
They are not designed for heating cargo areas used to carry hazardous substances.
The heaters operate independently of the vehicle engine and are connected to the fuel tank and to the vehicle's
electrical system.
They may be used for vehicles with either water or air-cooled engines.
1.2 Meaning of Signal Words
Throughout this manual, the signal words WARNING, IMPORTANT and NOTE have the following meanings:
WARNING: This heading is used to highlight operating instructions or procedures which, if not correctly followed, may
result in personal injury or fatal accidents.
IMPORTANT: This heading is used to highlight operating instructions or procedures which, if not correctly followed, may
result in damage to the equipment or its components.
NOTE: This heading is used to direct your attention to a special feature deemed essential to highlight.
1.3 Additional Documentation to be used
If necessary, the operating instructions, installation instructions and the vehicle-specific installation documentation can be
used additionally.
1.4 Statutory Regulations and Safety Instructions
In principle, the general accident prevention regulations and current works safety instructions are applicable. "General
safety precautions" which go beyond the scope of these regulations are listed below (see Section 1.4.2). Any special
safety regulations relevant to this instruction manual will be highlighted in the relevant sections or text passages of the
procedures.
1.4.1 Statutory Regulations Governing Installation
Type approvals according to ECE-R 10 (EMC) and ECE-R 122 (Heating) exist for the Air Top Evo 40 / Air Top Evo 55
Heater. For the approval number, see Chapter 4, "Technical Data"
The provisions of Appendix 7 of the guideline ECE-R 122 must mainly be observed for the installation.
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Air Top Evo 40 / Air Top Evo 55 Service Manual

NOTE: The specifications of this Directive are binding in the scope of the Basic Directive EEC/70/156 and/or
EC/2007/46 (for new vehicle models from 29/04/2009) and should also be observed in countries in which no special
regulations exist.
1.4.2 General Safety Precautions
The repair and commissioning of the unit may only be carried out by personnel trained by Webasto. The repair and
installation of the unit may only be carried out in accordance with the workshop manual and the installation
instructions.
The exhaust pipe end is to be routed downward, to the side or, with exhaust gas routing under the vehicle floor, up
to the proximity of the side or rear limitation of the cab or the vehicle.
The function of parts important for vehicle operation may not be impaired. It must not be possible for condensation
or water to collect in the exhaust pipe. Drain holes may be used.
Electrical lines, switching and control units of the heater must be positioned in the vehicle so that their proper
operation cannot be impaired under normal operating conditions.
The ECE-R 122 Appendix 9 3.1.1 must be complied with for the routing of fuel lines and the installation of additional
fuel tanks. The main points from this law:
–All fuel tanks used to supply the heater must comply with the following regulations:
(a) If a leak occurs, the fuel must flow off onto the ground without it coming into contact with hot parts of
the vehicle or the cargo.
(b) Fuel tanks containing benzin must be provided with an effective flame arrester at the filling opening or
with a cap with which the opening is kept hermetically sealed.
–The exhaust system and the exhaust lines must be positioned or protected so that the cargo cannot be
subjected to dangerous heat or ignition. Parts of the exhaust system located directly under the fuel tank
(diesel) must be positioned at a distance of at least 100 mm or must be protected by a heat shield.
The heat exchanger of the air heater may be used for a maximum of 10 years and must then be replaced
with a genuine spare part by the manufacturer or one of its authorized workshops. The heater must then
be provided with a sign which bears the date of sale and the words "Original Spare Part."
When replacing the heat exchanger, it is also mandatory to replace the Overheat Temperature Sensor in order to
prevent possible faults when using the old Overheat Temperature Sensor.
When installed in the vehicle interior, the Air Top Evo 40 / Air Top Evo 55 heaters must be prepared for installation
and sealing off directly on the cabin floor. With the accessories available from Webasto, detachable connections of
the combustion air and exhaust lines are not permitted in the vehicle interior.
The seal between the heater mounting and the vehicle floor must always be installed, otherwise harmful emissions
may get into the interior of the vehicle.
Cold and combustion air intake openings must be positioned so that no water can penetrate during a water crossing
permissible for the respective vehicle.
The combustion heater shall not constitute a risk of fire, even in the case of overheating. This requirement shall be
deemed to be met if the installation ensures an adequate distance to all parts and suitable ventilation, by the use of
fire resistant materials or by the use of heat shields. (Requirement from ECE-R 122, Point 5.3.2.2.).
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Air Top Evo 40 / Air Top Evo 55 Service Manual

In the case of M2 and M3 vehicles, the combustion heater must not be positioned in the passenger compartment.
However, an installation in an effectively sealed envelope which also complies with the conditions in paragraph
5.3.2.2 may be used. (Requirement from ECE-R 122, Point 5.3.2.3.).
The installation box must have sufficient external ventilation to ensure that a maximum temperature of 40°C is not
exceeded in the box. Malfunctions may occur if the temperature exceeds this level.
The heater must be switched off at filling stations and tank farms as a result of the risk of explosion.
Wherever inflammable vapors or dust may form (for example in the vicinity of fuel, carbon, wood dust or grain mill (or
the like), the heater must be switched off as a result of the risk of explosion.
The heater must not be operated in enclosed areas such as garages and workshops without an emissions extraction
system, even if you use the timer, because of the risk of asphyxiation and poisoning.
In case of longer-lasting smoke emission, unusual combustion noises or fuel odors, the heater must be shut down by
removing the fuse and may not be returned to operation again until after it has been checked by personnel trained by
Webasto. Claims can only be made if it can be verified that the claimant has complied with the servicing and safety
instructions.
The fuel lines may not make direct contact with the exhaust pipe and must be thermally insulated if necessary, as
otherwise there is a fire danger.
All fuel-carrying lines must be connected leak-tight, may not be damaged and must be inspected regularly (at least at
the same interval as the vehicle inspection).
NOTE: If damage to or leaks in the fuel line are determined, the heater may not be operated until the damage has
been eliminated by an authorized Webasto specialist workshop. Put the heater out of action by removing the fuse.
Overheating
Keep the cold air inlet and hot air outlet free of dirt and objects. Blocked air lines can result in an overheating switch-
off. After an overheating switch-off, the air routing must be checked for free passage and all materials which impair
the flow of air must be removed or damage to the air routing must be repaired by an authorized Webasto specialist
workshop.
Never remove the grille in front of the cold air inlet.
The fault lock-out must be eliminated by switching the heater off and then on again. If these measures are
unsuccessful (overheating occurs again), the vehicle must be taken to an authorized Webasto specialized workshop.
The air outlet jets or air vents with adjustable flaps must always be opened to some extent so that the air current
through the heater is not completely blocked. At least one air outlet must be non-closable.
If the heater is installed in a storage area, you must ensure that no flammable substances are kept in this area and
that other material does not restrict the air supply to the heater.
Air lines must be firmly secured on the heater and at all other connection points (e.g. air outlets) (e.g. with pipe
clamps).
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Air Top Evo 40 / Air Top Evo 55 Service Manual

IMPORTANT:
•The heater may not be exposed to temperatures of more than 85°C (storage temperature). Otherwise the
electronics may suffer permanent damage.
•Do not stand on the heater and do not place any heavy items on the heater.
•Do not place any items of clothing, textiles, or similar material over the heater or in front of the cold air inlet
and the hot air outlet.
•The current of hot air in the heater must not be restricted or blocked by highly inflammable substances or
materials such as rags, cleaning wool, etc.
•Flammable or explosive substances and gases must not be placed near or in contact with the heater, the hot
air line, the hot air flow or the exhaust pipe.
•The heater must not be cleaned with a high pressure cleaner.
•Do not switch the heater off at the main battery switch or battery isolation switch, since otherwise it is
possible that it may suffer long term damage if it is switched off frequently using the battery isolation switch
and this can cause damage and negative influences on the function of the heater.
Liability Claims
Failure to follow the installation instructions and the notes contained therein will lead to all liability being refused by
Webasto.
The same applies if repairs are carried out incorrectly or with the use of parts other than genuine spare parts. This will
result in the heater's warranty being voided, and therefor also of the General Homologation/ECE Type Approval.
Be sure to read the operating instructions before putting the heater into operation.
2. General Description
The Air Top Evo 40 / Air Top Evo 55 air heater designed according to the evaporator principle mainly consists of the
following:
–The drive unit (drive motor with combustion and heating air fan)
–The heat exchanger
–The evaporator mount with combustion pipe
–The control unit
–The glow plug
–The housing parts
–The base seal
To control and monitor it, the heater has the following internal components:
–A control unit with room temperature sensor, speed sensor (Hall sensor) and air pressure sensor
–An overheat temperature sensor
–An exhaust temperature sensor
The fuel supply is ensured externally via a fuel pump. The heater can be controlled with an internal room temperature
sensor or an external room temperature sensor (optional).
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Air Top Evo 40 / Air Top Evo 55 Service Manual

Figure 1: Air Top Evo 40/55 Air Heater Figure 2: Air Top Evo 40/55
Air Heater (without housing)
2.1 Drive Unit
The drive unit consists of the drive motor, the combustion air fan, the heating air fan and the intake housing.
The combustion air fan supplies the air required for the combustion process from the combustion air inlet to the
evaporator mount. The heating air fan transports the cold air from the cold air inlet to the hot air outlet via the heat
exchanger.
Figure 3: Drive Unit
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Air Top Evo 40 / Air Top Evo 55 Service Manual

2.2 Heat Exchanger
The heat generated by combustion in the heat exchanger is given off to the cold air transported by the heating air fan.
Figure 4: Heat Exchanger
2.3 Evaporator Mount with Combustion Pipe
The fuel is distributed via the metal fibre evaporator (fleece) in the evaporator mount. The mixture of fuel and air burns in
the combustion chamber, thus causing the heat exchanger to become hot.
Figure 5: Evaporator Mount with
Combustion Pipe (Diesel)
Figure 6: Evaporator Mount with
Combustion Pipe (Benzin)
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Air Top Evo 40 / Air Top Evo 55 Service Manual

2.4 Glow Plug
The mixture of fuel and air is ignited by the glow plug when the heater is started. The glow plug designed as an electrical
resistor is positioned in the burner assembly (evaporator mount with combustion pipe) on the side facing the flame.
Figure 7: Glow Plug
2.5 Exhaust Temperature Sensor
The exhaust temperature sensor is a low-resistance PTC resistor which changes its resistance in dependence on the
temperature change of the exhaust gases. This change in resistance is also used for flame monitoring.
Figure 8: Exhaust Temperature Sensor
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Air Top Evo 40 / Air Top Evo 55 Service Manual

2.6 Overheat Temperature Sensor
The overheat temperature sensor measures the temperatures in the fin area of the heat exchanger during the entire
heater operation.
The control unit evaluates the signal and regulates the hot air outlet temperature and controls the overheating switch-off.
Figure 9: Overheat Temperature Sensor
2.7 Control Unit
The control unit is the central component for ensuring the operating sequence. It monitors the components, evaluates the
signals of the sensors and regulates the heating mode.
Figure 10: Control Unit
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Air Top Evo 40 / Air Top Evo 55 Service Manual

2.8 Fuel Pump
The fuel pump is a combined pumping, metering and shut-off system for the heater fuel supply.
The Air Top Evo 40 / Air Top Evo 55 heaters must be operated with the DP 42 fuel pump.
Figure 11: Fuel Pump
3. Function Description
3.1 Control Element
Air Top Evo 40 / Air Top Evo 55 can be activated either with suitable control elements, e.g. rheostat, Smartemp, or an Air
Top Evo Multi Control (MC04).
Operation is described in the operating instructions of the respective control element.
The control element is used to switch the heater on and off, to set the desired room temperature (between approx. 5 °C
and 35 °C) and the operating indicator.
The installed operating indicator is used:
–As switch-on check
–As a fault signal and
–As a service display
Additional comfort functions (Eco, Normal, Plus and Ventilation) can be controlled with the Air Top Evo Multi Control
(MC04) control element.
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Air Top Evo 40 / Air Top Evo 55 Service Manual

3.2 Switching On
Switch on heater.
Set the control element to the required temperature.
The starting process begins when the room temperature is below the set point temperature.
Note: If the room temperature is above the selected set point temperature, only the drive motor with the combustion
and heating air fan runs. When an external room temperature sensor is connected, the drive unit does not run.
Before starting, a plausibility test of the temperature sensors is carried out and the function of the exhaust-temperature
flame monitor is checked. If the flame monitor now reports “light”, the system will attempt to cool the flame monitor for
up to 100 seconds. If the flame monitor still reports “light” the control unit will suffer a fault lock-out. Also see 3.8
Fault Switch-Off.
Start
When the heater is switched on the operating display will be lit and the glow plug will be switched on (cycled). The drive
motor with the combustion and heating air fan is adjusted to approx. 50 % of the maximum speed.
After approximately 40 seconds, the fuel pump is put into operation and flame formation begins. To improve the starting
quality, the fuel pump and the drive unit are controlled with different frequencies and speeds.
After a further 80 to 120 seconds, the glow plug will be switched off and the existence of the flame established.
Automatic restart
If the flame monitor does not find a flame, the starting procedure will be repeated. The glow plug will be switched on
again (cycled). The drive motor with the combustion and heating air fan is adjusted to approx. 50 % of the maximum
speed.
After approximately 40 seconds, the fuel pump is put into operation and flame formation begins.
After a further 80 to 120 seconds the glow plug will be switched off and the existence of the flame established.
If the heater has again failed to ignite properly, then it will be shut down using a fault slow down procedure at maximum
speed after approximately 240 seconds and will suffer a fault lock-out.
Note: After restarting, a fault lock-out of the heater is carried out. To reset the fault, switch the heater off briefly (at least
2 seconds) and then on again.
3.3 Heating Mode
While the heater is operating, the combustion gases pass through the heat exchanger. In the process, the combustion
heat is given off to the walls of the heat exchanger, absorbed by the cold air transported by the heating air fan and
routed into the vehicle interior.
The temperature of the cold air intake is measured by a room temperature sensor in the control unit or an external room
temperature sensor. If the measured temperature is less than is set on the control element, the heater output increases to
the maximum heating capacity.
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Air Top Evo 40 / Air Top Evo 55 Service Manual

To increase the burner service life in continuous operation, the delivery capacity of the fuel pump is reduced for 10
seconds every 10 minutes.
In addition, the heating mode is briefly interrupted after every 8 hours and then automatically restarted in the same way
as for a control break. This ensures controlled combustion operation.
3.4 Control Mode
In the control mode, the drive motor speed and the fuel pump quantity are dependent on the heating capacity. The glow
plug is off.
3.5 Control Break
After the temperature set on the control element has been reached the heat output is reduced. The speed of the
combustion and heating air fan and the pumping quantity of the fuel pump are reduced.
If, at minimum heat output, the intake temperature set on the control element is exceeded, the fuel pump is shut down
and the combustion process ended. To burn off the flame properly, the drive motor speed falls after 20 seconds to partial
load speed and then returns to the initial speed after 20 seconds, after which it falls to the control break speed in
approximately 90 seconds, where it remains for the entire control break.
The control break speed is 0 if an external room temperature sensor is used.
If the temperature set on the control element is dropped below the room temperature sensor, the heater starts again.
Note: Changes to the setting on the control element are implemented by the control unit and heater after a delay.
3.6 Switching Off
When the heater is switched off, the operating display on the control element goes out. If no fuel has been transported
yet or if the heater is in the control break, the heater is switched off immediately without a run-on period.
If the fuel transport has been started it is ended when the heater is switched off. The heater is switched off using the
same method as the transition from control mode to control break. The heater is then switched off automatically.
Note: It is permissible to switch on the heater again during the run-on. In this case the run-on is completed and the
heater is then restarted.
3.7 Functions of Air Top Evo System
3.7.1 Installation/Commissioning
Installation
1. Installation of the heaters in accordance with Air Top Evo 40 / Air Top Evo 55 installation instructions.
2. Ensure that the electrical connections are in accordance with the wiring diagram (Figure 15, Figure 16, Figure 17).
3. Installation of control element and external room temperature sensor.
Note: When the heaters are switched on, the system automatically configures itself as master and slave.
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Air Top Evo 40 / Air Top Evo 55 Service Manual

3.8 Fault Switch-Off
Errors on the various heater components and faults in the starting process and in heating mode are identified in the
control unit. For safety reasons, the fuel pump will be switched off after all detected faults. The heater is switched off and
switches into the fault lock-out mode.
For details, see chapter 5.0 Troubleshooting.
3.8.1 Error Monitoring
The overheating, incorrect start and flame abort errors are counted and cause the heater to suffer a fault lock-out
after an error has occurred the maximum number of times.
The incorrect start counter is increased by 1 each time the heater fails to start. If the incorrect start counter reaches its
maximum permissible value of 9, then the heater is in the heater lock-out status.
The fault counter is increased by 1 for each malfunction for which there is no separate counter. If the fault counter
reaches its maximum permissible value of 5, then the heater is in the heater lock-out status.
The overheating counter is increased by 1 each time the heater overheats. If the overheating counter reaches its
maximum value of 5, then the heater is in the heater lock-out status.
After a flame abort, a restart is automatically carried out. The condition for a restart is that the heater was in the
control mode directly beforehand. During the restart the cycle repetition counter is increased by one. This process is
repeated until the heater either burns properly again or the maximum value of 3 for the cycle repetition counter has
been reached.
The flame abort counter FAZ is increased by 1 when the cycle repetition counter ZWZ has reached the maximum
value. If the flame abort counter reaches its maximum value of 3 the heater will go into the heater lock-out status.
Automatic reset:
Following each heater start-up, the cycle repetition counter is set to 0. The fault counter is set to 0 after a fault-free
transition to the control mode and the flame abort counter, overheating counter, false starting counter and cycle
repetition counter are set to 0 after (!) fault-free combustion operation (20 min.).
3.8.2 Reset a Fault Switch-Off
1. Switch on heater. ↓
2. An error has occurred and is detected by the control unit as a fault. ↓
3. The error code is displayed via the control element. ↓
4. Any active heater lock-out is cancelled (as described below). ↓
4.1 The heater detects an error as a fault. ↓
4.2 Fault switch-off with subsequent fault lock-out. ↓
4.3 The error code is displayed via the control element. ↓
5. Switch off heater. ↓
6. Determine error cause (e.g. with or without error code, visual inspection of fuses and connectors, etc.) ↓
7. Eliminate error. ↓
8. Switch on heater. ↓
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Air Top Evo 40 / Air Top Evo 55 Service Manual

9. Fault lock-out unlocked. ↓
10. The heater switches into the control mode.
Certain errors result in the errors being added up in the error memory. If the number of errors in the error memory
have exceeded a limit, the heater changes over to the heater lock-out. The maximum number of errors in the error
memory or the error memory limit is defined by Webasto.
Cancel Heater Lock-Out
The heater lock-out can be cancelled:
–With the Webasto Thermo Test PC Diagnostics (WTT)
–Or by switching on the heater.
1. Remove fuse f1 for at least 10 s.
2. Switch off heater.
3. Reinstall fuse f1.
4. Switch on heater.
Cancel Permanent Heater Lock-Out
Unlocking is only carried out with the vehicle-specific computer diagnosis.
4.0 Technical Data
Except where limit values are specified, the technical data listed in the table refer to the usual heater tolerances of ±10% at
an ambient temperature of +20 °C and at the rated voltage and in rated conditions.
Electrical components:
The control unit, timer, glow plug and control element are designed for 12V or 24V.
The drive unit, fuel pump, exhaust temperature sensor and external room temperature sensor are independent of voltage.
Fuel for Air Top Evo 40 B / Air Top Evo 55 B (benzin): The fuel specified by the manufacturer in accordance with DIN EN
228 must be used.
Fuel for Air Top Evo 40 D / Air Top Evo 55 D (diesel/PME): The diesel fuel specified by the manufacturer in accordance
with DIN EN 590 must be used. We know of no negative influences due to additives. If fuel is extracted from the vehicle’s
tank, follow the additive instructions issued by the vehicle manufacturer. If you change to low-temperature fuel, the heater
must be operated for approximately 15 minutes so that the fuel system is filled with the new fuel. The Air Top Evo 40 D / Air
Top Evo 55 D unit is also approved for operation with PME (bio-diesel) which complies with the standard DIN EN 14214.
About table: Values in brackets apply to the increased heating capacity which is activated for a limited time during each start-
up.
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Air Top Evo 40 / Air Top Evo 55 Service Manual

Heater
Operation
Air Top Evo 40B
Air Top Evo 55B
Air Top Evo 40 D
Air Top Evo 55 D
Type test permit
EMC: E1 03 5529 (Air Top Evo 40 / Air Top Evo 55)
Heater: E1 00 0385 (Air Top Evo 40)
Heater: E1 00 0386 (Air Top Evo 55)
Model Air heater with evaporation burner
Heat output
Control range
1.7 to 3.5 (4.0) kW
1.7 to 5.0 (5.5) kW
1.5 to 3.5 (4.0) kW
1.5 to 5.0 (5.5) kW
Fuel
Petrol
DIN EN 228
Diesel/Bio-Diesel
DIN EN 590
DIN EN 14214
Fuel consumption
Control range
0.18 to 0.38 (0.43) kg/h
0.25 to 0.51 (0.58) l/h
0.18 to 0.54 (0.59) kg/h
0.25 to 0.73 (0.80) l/h
0.15 to 0.36 (0.41) kg/h
0.18 to 0.43 (0.49) l/h
0.15 to 0.51 (0.56) kg/h
0.18 to 0.61 (0.67) l/h
Ratedvoltage
12 V
12/24 V
Operating voltage range 10.5 to 16 V 10.5 to 16 V/20.5 to 31 V
Rated power consumption
Control range
15 to 40 (55) W
15 to 95 (130) W
15 to 40 (55) W
15 to 95 (130) W
Permissible ambient
temperature:
Heater – Operation
– Storage
Fuel pump – Operation
– Storage
Rotary selector – Operation
– Storage
–40 °C to +40 °C
–40 °C to +85 °C
–40 °C to +20 °C (petrol), +30 °C (diesel)
–40 °C to +85 °C
–40 °C to +75 °C
–40 °C to +85 °C
Permissible combustion air
intake temperature
–40 °C to +20 °C
Adjustment range for room
temperature
Control range +5 °C to +35 °C
Volume flow rate of hot air against 0.5 mbar max. 132 (140) m
3
/h max. 200 (220) m
3
/h max. 132 (140) m
3
/h max. 200 (220) m
3
/h
Heater dimensions Length: 423 ± 2 mm
Width: 148 ± 1 mm
Height: 162 ± 1 mm
Heater weight 5.9 kg
Technical Data Air Top Evo 40 / Air Top Evo 55
12V
24V
Glow plug At 25 °C
Test current: < 5 mA
No marking
0.190 - 0.250 ohms
Green marking 0.740 -
0.940 ohms
Drive unit
Outside
< 6 ohms
Overheat Temperature Sensor
at 25 ºC
2,195 ohms
External temperature sensor
at 25 ºC
10,000 ohms
Exhaust temperature sensor
2,160 ohms
Under-voltage switch-off (triggering time > 20 s ) ≤ 10,5 V ≤ 20.5 V
Over-voltage switch-off (triggering time > 6 s )
≥ 16 V
≥ 31 V
Setpoint Values for Resistance Values of Components
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Air Top Evo 40 / Air Top Evo 55 Service Manual