List of Contents
Air Top 2000
Air Heater
Air Top 2000 S D (Diesel)
Air Top 2000 S B (Gasoline)
Service and Repair 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.
– Installation and repair of Webasto heating and cooling systems requires special
Webasto training, technical information, special tools and special equipment.
– NEVER attempt to install or repair a Webasto heating or cooling system unless you
have successfully completed the factory training course and have the technical skills,
technical information, tools and equipment required to properly complete the
necessary procedures.
– 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.
Air Top 2000 S
List of Contents
List of Contents
1. Introduction
1.1 Scope and Purpose.................................................................................................................................101
1.1.1 Use of Air Heaters.......................................................................................................................101
1.2 Meaning of Warnings, Cautions, and Notes............................................................................................101
1.3 Additional Documentation to be used...................................................................................................... 101
1.4 Safety Information and Regulations ........................................................................................................101
1.4.1 General Safety Notes..................................................................................................................101
1.5 Legal Provisions for Installation...............................................................................................................102
2. General Description
2.1 Combustion and Heating Air Fan ............................................................................................................201
2.2 Heat Exchanger....................................................................................................................................... 202
2.3 Burner Insert with Combustion Tube.......................................................................................................202
2.4 Control Unit / Control Circuit Board.........................................................................................................202
2.5 Flame Sensor ..........................................................................................................................................203
2.6 Glow Plug ................................................................................................................................................203
2.7 Temperature Limiter ................................................................................................................................ 203
2.8 Dosing Pump...........................................................................................................................................203
3. Functional Description
3.1 Functional Description Air Top 2000 S .......................................................................................................301
3.1.1 Control Element ..........................................................................................................................301
3.1.2 Switch-On....................................................................................................................................301
3.1.3 Stabilization.................................................................................................................................301
3.1.4 Heating Operation.......................................................................................................................302
3.1.5 Control Operation........................................................................................................................ 302
3.1.6 Control Idle..................................................................................................................................302
3.1.7 Switch-Off....................................................................................................................................302
3.1.8 Switch-Off upon Failure...............................................................................................................302
4. Technical Data ............................................................................................................................................... 401
5. Troubleshooting
5.1 General....................................................................................................................................................501
5.2 General Failure Symptoms......................................................................................................................501
5.3 Failure Symptoms during Operation........................................................................................................502
5.4 Error Code Output ......................................................................................................................................503
6. Functional Tests
6.1 General....................................................................................................................................................601
6.2 Adjustments.............................................................................................................................................601
6.2.1 Adjustment of the CO
6.3 Components Testing ...............................................................................................................................602
6.3.1 Glow Plug Resistance Test .........................................................................................................602
6.3.2 Flame Sensor Resistance Test ...................................................................................................602
Contents.................................................................................................601
2
I
List of Contents
7. Circuit Diagrams
7.1 General....................................................................................................................................................701
8. Servicing
8.1 General....................................................................................................................................................801
8.2 Work on the Air Heater............................................................................................................................801
8.3 Work on the Vehicle ................................................................................................................................801
8.4 Air Heater Test Run.................................................................................................................................801
8.5 Servicing..................................................................................................................................................801
8.6 Visual Inspections and Installation Regulations ......................................................................................801
8.6.1 Heating Air System......................................................................................................................801
8.6.2 Fuel Supply .................................................................................................................................802
8.6.3 Dosing Pump...............................................................................................................................804
8.6.4 Fuel Filter ....................................................................................................................................804
8.6.5 Combustion Air Supply................................................................................................................805
8.6.6 Exhaust Line ...............................................................................................................................805
8.6.7 Combustion Air Intake and Exhaust Lines ..................................................................................805
8.6.8 Electrical Connections.................................................................................................................806
Air Top 2000 S
8.7 Removal and Installation .........................................................................................................................808
8.7.1 Air Heater, Removal and Installation...........................................................................................808
8.8 Start-Up...................................................................................................................................................808
9. Repair
9.1 General....................................................................................................................................................901
9.1.1 Work on Components after Disassembly....................................................................................901
9.1.2 Incorporation of Modifications .....................................................................................................901
9.2 Disassembly and Assembly.....................................................................................................................902
9.2.1 Removal of Housing Components/Covers.................................................................................. 902
9.2.2 Replacement of Control Unit.......................................................................................................903
9.2.3 Replacement of Temperature Limiter..........................................................................................903
9.2.4 Replacement of Combustion Air Fan ..........................................................................................905
9.2.5 Replacement of Flame Sensor....................................................................................................907
9.2.6 Replacement of Glow Plug..........................................................................................................907
9.2.7 Replacement of Burner Insert, Combustion Tube, and Heat Exchanger.................................... 910
10. Packaging/Storage and Shipping
10.1 General..................................................................................................................................................1001
II
Air Top 2000 S
List of Figures
List of Figures
501 General Failure Symptoms .............................................................................................................................501
502 Failure Symptoms during Operation ...............................................................................................................502
601 Adjustment of CO
701 Terminal Pin Assignment, Air Top 2000 S.......................................................................................................701
702 Circuit Diagram Automatic Control Air Top 2000 S, 12V/24V with Control D i a l ............................................702
703 Circuit Diagram Automatic Control Air Top 2000 S, 12V/24V with Combination Timer ..................................703
704 Circuit Diagram Automatic Control Air Top 2000 S,
12V/24V with Control Dial and Standard Timer ..............................................................................................704
705 Connection Diagram, Air Top 2000 S with Combination Timer.....................................................................705
801 Fuel Supply.....................................................................................................................................................802
802 Webasto Fuel Tank Tap .................................................................................................................................803
803 Fuel Tapping from Plastic Tank (tapping via fuel drain plug)..........................................................................803
804 Fuel Tapping from Plastic Tank (tapping via fitting plate)...............................................................................803
805 Pipe/Hose Connection....................................................................................................................................804
806 Dosing Pump, Installation Position and Attachment .......................................................................................804
807 Fuel Filter........................................................................................................................................................804
808 Exhaust Muffler, Direction of Flow..................................................................................................................805
809 Exhaust Pipe Outlet, Installation Position .......................................................................................................805
810 Weather Resistant Fuse Holder........................................................................................................................806
811 Control Di a l ...................................................................................................................................................806
812 Pulling the Plug...............................................................................................................................................806
813 Example of an Installation...............................................................................................................................807
901 Removal of Housing Components/Covers......................................................................................................902
902 Replacement of Control Unit and Temperature Limiter...................................................................................904
903 Replacement of Combustion Air Fan (Disassembly) ......................................................................................905
904 Replacement of Combustion Air Fan (Assembly............................................................................................906
905 Disassembly of Heat Exchanger (Sheet 1 of 2 ) ..........................................................................................908
906 Disassembly of Heat Exchanger (Sheet 2 of 2 ) ..........................................................................................909
Contents ..........................................................................................................................601
2
III
List of Figures
Air Top 2000 S
IV
Air Top 2000 S
1 Introduction
1. Introduction
1.1 Scope and Purpose
This repair shop manual is intended to support familiarized personnel in the repair of the Air Top 2000 S.
1.1.1 Use of Air Heaters
The air heater Air Top 2000 S is used to
- heat the cabin
- defrost the windscreens.
They are not cleared for heating a transportation compartment for dangerous goods.
The heaters operate independent from the vehicle engine and are connected to the fuel tank and to the electrical system of the vehicle. Their use is possible in
vehicles with water- or air-cooled engines.
1.2 Meaning of Warnings, Cautions
and Notes
WARNINGS, CAUTIONS, and NOTES in this manual
have the following meaning:
WARNING
This heading is used to highlight that non-compliance
with instructions or procedures may cause injuries or
lethal accidents to personnel.
CAUTION
This heading is used to highlight that non-compliance
with instructions or procedures may cause damage to
equipment.
NOTE
This heading is used to highlight and draw specific attention to information.
1.4 Safety Information and Regulations
The general safety regulations for the prevention of accidents and the relevant operating safety instructions have
to be observed at all times."General Safety Regulations"
beyond the scope of these regulations are detailed in the
following.The specific safety regulations applicable to
this manual are highlighted in the individual chapters by
Warnings, Cautions, and Notes.
1.4.1 General Safety Notes
Within the scope of the StVZO (Road Licensing Regulations of the Federal Republic of Germany) “Design
General Approvals”, laid down by the Federal Office for
Motor Traffic, exist for the Air Top 2000 S with the
following official marks of conformity:
-S 324 (Diesel)
-S 325 (Gasoline)
The installation of the heater is to be performed in accordance with the installation instructions and must be
checked in case of
a) the vehicle type inspection in accordance with
§ 20 StVZO
b) the individual inspection in accordance with
§ 21 StVZO or
c) the examination in accordance with § 19 StVZO
performed by an officially authorised expert or examiner for road traffic, a vehicle inspector or a public
servant as per section 7.4 a of Annex VIII to the
StVZO.
In the event of c) the installation must be certified on the
acceptance certificate included in the copy of the
“General Operating License” giving details about
- manufacturer
- type of vehicle , and
- vehicle identification number.
This validates the “Design General Approval”.
The acceptance certificate must be kept with the
vehicle.
The year of first operation must be permanently
marked on the identification label.
1.3 Additional Documentation to be used
This workshop manual contains all information and procedures necessary for the repair of the Air Top 2000 S.
The use of additional documentation is normally not
necessary.
Operating instructions/installation instructions and the
vehicle specific installation proposal may be used as
complementary information as necessary.
The heaters are cleared for heating the passenger and
driver cabins but not for heating compartments intended
for the transportation of dangerous goods.
101
1 Introduction
Air Top 2000 S
The heater must not be installed in the passenger or
driver compartments of busses. Should the heater nevertheless be installed in such a compartment, the installation box must be sealed tight against the vehicle interior.
There must be sufficient ventilation of the installation box
from the exterior in order not to exceed a maximum temperature of 40 °C in the installation box.
At filling stations and fuel depots the heater must be
switched off as there is a potential danger of explosion.
Where flammable fumes or dust may build up (e.g.
in the vicinity of fuel, coal, wood, cereal depots, or
similar installations) the heater must be switched off
to prevent explosions.
Due to the danger of poisoning and suffocation the
heater must not be operated in enclosed areas such as
garages or workshops without exhaust venting, not even
if the start-up is activated by the timer or telestart device.
When removing the heater the gasket below must be replaced.
The heat exchanger of the air heater remains serviceable for a maximum of 10 years and must then be replaced with an original spare part by the manufacturer or by one of its authorized workshops.
The heater must then be provided with a label
marked with the sales date and with the words “Original Spare”.
Should exhaust pipes be routed through rooms
accommodating persons, these pipes shall also be
renewed after 10 years.
Heating Air System
Heating air intake openings must be arranged so that
under normal operating conditions exhaust fumes of the
vehicle engine or air heater are not likely to be expected.
Extracting combustion air from the vehicle interior is not
permissible.
Combustion Air Line
The combustion air required must be taken from the
exterior.
Within rooms accommodating persons, the combustion
air lines must not have more than four disconnects and a
splash-water protected exterior wall feedthrough. The
disconnects must be sealed in a way not to exceed a
leak rate of 200 l/h at an overpressure of 0.5 mbar.
The line including feedthrough, disconnects, material
and specific type must be described in the installation
instructions.
The line must require tools for installation and removal,
must be protected against damage, and must be shockproof.
Exhaust Line
Heaters must be designed to discharge the exhaust to
the exterior.
Exhaust pipes must be routed so that exhaust fumes are
unlikely to penetrate into the vehicle’s interior.
The function of any parts of the vehicle essential for its
operation must not be impaired. Condensate or water
penetrated must not be able to accumulate in the
exhaust line.
Drain holes are permissible; these must drain the fluid to
the exterior via lines sealed against the vehicle interior.
Installations not legally authorized will void the air
heater’s “Official Marks of Conformity” and thus the
vehicle’s permit of operation. The same applies for
repairs performed by unskilled personnel and repairs
with no original spare parts.
1.5 Legal Provisions for Installation
For testing the heater in accordance with 19, 20, or 21
of the StVZO the following regulations are to be observed in particular (§ 22 a StVZO):
Testing is performed upon presentation of the operating
and installation instructions of the manufacturer.
The year of the initial operation must be durably marked
on the heater identification plate by the installing person.
The exhaust line outlet is to be positioned to the top, to
the side, or in case of exhaust venting below the vehicle
floor, to the nearest possible location of the vehicle’s or
cockpit’s side or rear end. In compartments accommodating persons, exhaust lines must not have more than
one disconnect and must have a splash-water protected
feedthrough in the exterior wall/floor. For water, that has
penetrated into the exhaust line, the connection of a
drain line with a metal-sealing joint is permissible. The
drain pipe must be routed sealed through the exterior
wall or the vehicle floor.The heat exchanger, the exhaust
line connected, as well as the possible drain pipe must
be sealed so that with an overpressure of double the
overpressure of the exhaust having the maximum permissible exhaust line length - at least however at an overpressure of 0.5 bar - a total leak rate of 30 l/h is not
exceeded.
The line including feedthrough, disconnects, material
and specific type must be described in the installation
instructions.
The line must require tools for installation and removal,
must be protected against damage, and must be shockproof.
102
Air Top 2000 S
Metal lines must be used. These may not heat to more
than 110 °C should there be the possibility of contact
within the room interior. Protective devices against contact may be fitted.
Should exhaust pipes be routed through rooms accommodating persons, these pipes shall be renewed after 10
years using genuine spare parts.
Combustion Air Inlet and Exhaust Outlet
During installations these ports for combustion air entry
and exhaust fume exit must be of such type, that a ball
with a diameter of 16 mm cannot be inserted. Electrical
lines, switch gear and control gear of the heater must be
located in the vehicle so that their proper function cannot
be impaired under normal operating conditions.
For the routing of fuel lines and the installation of additional fuel tanks §§ 45 and 46 of the StVZO are to be
adhered to.
The most important regulations are: Fuel lines are to be
designed in such a way that they remain unaffected by
torsional stresses in the vehicle, engine movement and
the like. They must be protected against mechanical
damage.
Fuel-carrying parts are to be protected against excessive heat and are to be arranged so that any dripping
or evaporating fuel can neither accumulate nor be ignited by hot components or electrical equipment.
In busses, fuel lines and fuel tanks may be located
neither in the passenger area nor in the driver’s compartment. In these type of vehicles the fuel tanks must be located such that they do not pose a direct hazard to the
exits in the event of a fire. Fuel supply must not be by
means of gravity or pressurization of the fuel tank.
1 Introduction
Installation Rules for Webasto Fuel Tanks for the
Fuel Supply of Heaters in Vehicles
In busses the installation is not permitted in the passenger or driver compartment.
The fuel fill neck must in no vehicle be located within any
of these compartments.
Fuel containers for gasoline fuel must not be located
immediately behind the front panelling of the vehicle.
They must be sparate from the engine so that even in
case of an accident the inflammation of fuel is unlikely to
be expected. This does not apply for towing vehicles
with an open cockpit.
The operational state of the heater, i.e. an indication “on”
or “off”, must be easily and clearly visible.
103
2 General Description
Air Top 2000 S
2. General Description
The air heater Air Top 2000 S operates under the
evaporator principle and basically consists of:
- combustion and heating air fan
- heat exchanger
- burner insert with combustion tube
- control unit
A malfunction of the Air Top 2000 S is indicated by an
error code displayed on the combination or standard
timer. When equipped with the standard control dial,
the operating indicator flashes. In addition a heater check
out may be performed using a personal computer (refer
to operating instructions PC air heater diagnosis).
Air Heater Air Top 2000 S
(covers removed)
Air Heater Air Top 2000 S
For control and monitoring a
- control unit/control circuit board
- flame sensor
- glow plug
- temperature limiter
- temperature sensor
are located within the unit.
All Air Top 2000 S heaters may be controlled
by means of an optional external temperature sensor.
Fuel supply is provided externally by a fuel dosing pump.
2.1 Combustion and Heating Air Fan
The combustion and heating air fan delivers the air required for combustion from the combustion air inlet to
the burner insert. By means of the fan the heating air is
also delivered to the hot air outlet.
Combustion and Heating Air Fan
201
Air Top 2000 S
2 General Description
2.2 Heat Exchanger
The heat exchanger dissipates the heat provided by
combustion to the air delivered by the combustion and
heating air fan.
Heat Exchanger
2.4 Control Unit / Control Circuit Board
The control unit/control circuit board is the central controlling unit for functional sequencing and monitoring of
the combustion operation. A temperature sensor located
on the control unit is used for temperature control. All
heaters may have the temperature sensor replaced
with an external temperature sensor. The combustion
and heating air fan may be set by means of a potentiometer.
A malfunction in the Air Top 2000 S is indicated by an
error code displayed on the combination or standard
timer. When equipped with a standard control dial
the operating indicator flashes. In addition a heater check
out may be performed using a personal computer (refer
to operating instructions PC air heater diagnosis).
Potentiometer
2.3 Burner Insert with Combustion Tube
Within the burner insert fuel is distributed in the combustion tube across the burner cross-section. In the combustion tube the combustion of the fuel/air mixture takes
place heating up the heat exchanger.
Combustion
Tube
Burner
Insert
Temperature
Sensor
Control Unit - Air Top 2000 S
Diesel
2 mm
Fuel
1 mm
202
2 General Description
Air Top 2000 S
2.5 Flame Sensor
The flame sensor is a low-Ohm PTC resistor changing
its resistance dependent on its heating by the flame.
The signals are routed to the control unit for processing.
The flame sensor monitors the flame operating condition
over the complete duration of heater operation.
Flame Sensor
2.6 Glow Plug
2.7 Temperature Limiter
The temperature limiter protects the air heater against
excessive operating temperatures. Overheat protection
is activated at a temperature higher than 150 °C to interrupt the electrical circuit of the dosing pump and switch
off the heater with run-down operation.
After cooling down the electrical circuit is restored.
The air heater may be switched on again (see 3.1.8).
Temperature Limiter
The glow plug ignites the fuel/air mixture at the start of
the air heater operation. The glow plug is acting as an
electrical resistor and is located in the burner insert
opposed to the flame side.
Glow Plug
2.8 Dosing Pump
The dosing pump is a combined supply, dosing and shutoff system for the fuel supply of the heater out of the
vehicle’s fuel tank.
Dosing Pump DP 2 for Gasoline and Diesel
operated Heaters
203
Dosing Pump DP 30 for Diesel operated Heaters
Air Top 2000 S
3. Functional Description
3 Functional Description
3.1 Functional Description Air Top 2000 S
3.1.1 Control Element
The control element is used to switch the air heater on
and off, set the desired room temperature (air intake temperature between 10 °C and 45 °C), and to unlock a
failure interrupt condition.
The green LED indication is used to indicate the operating condition (LED permanently on) and an overheat
condition (LED flashes).
3.1.2 Switch-On
The control element is set to the desired room temperature. When switching the air heater on, the operating indicator is illuminated and the glow plug is activated
(cycled). The motor of the combustion and heating air
fan starts high-speed operation for 1 second (breakaway moment) and is then under slow-down control to
approx. 30% (Diesel) or 50% (fuel) of full speed.
NOTE
Should the temperature of the intake air be above the selected, rated temperature, only the motor of the combustion and heating air fan will operate (control idle). Start
operation will be initiated with a heating air temperature
below the rated temperature.
The flame sensor function is checked. If the flame sensor at this time already signals “flame”, there will be a
120 second run-down and an error lockout of the control
unit. A malfunction of any other component monitored
causes an error lockout without run-down.
After approx. 20 seconds (for fuel operated heaters after
approx. 15 seconds) the fuel dosing pump is activated.
After another 25 seconds the speed of the combustion
and heating air fan is continuously increased to a higher
rate and combustion begins. As soon as a flame is
detected, combustion will be stabilized (see 3.1.3).
Should no normal combustion be achieved within 120
seconds (for fuel operated heaters after approx. 115
seconds), the speed of the combustion and heating air
fan is increased for approx. 30 sec and there will be an
automatic repeat start with the glow plug activated and
fuel dosing pump deactivated (no fuel supply).
Should no proper combustion develop within 120 seconds (for fuel-operated within 115 seconds) the combustion and heating air fan speed is increased to full load for
approx. 30 seconds (15 seconds for fuel-operated
heaters) with the glow plug on and the dosing pump off
(no fuel delivery) with a subsequent automatic restart.
Should the no-combustion-condition persist, after another 80 seconds (for fuel operated heaters after approx.
85 seconds) there will be a switch-off by error lockout
(see 3.1.8) with a run-down of the combustion and heating air fan lasting 120 seconds at 2/3 of its max. speed.
2. Start (automatic restart)
Fan speed is again reduced to approx. 30% (for fuel
operated heaters to approx. 50%) and fuel is delivered.
During the next 20 seconds fan speed is increased to approx. 60% (for fuel-operated heaters to approx. 75%) of
full speed. As soon as a flame is detected within the next
55 seconds, combustion will be stabilized. Should there
be no flame condition after a total fuel delivery period of
180 seconds, fuel delivery will be stopped and the glow
plug deactivated. The combustion air fan continues full
load operation for another 120 seconds (run-down) and
the heater enters the error lockout condition.
3.1.3 Stabilization
Diesel Operated Heaters
With the glow plug activated the operating speed of the
combustion and heating air fan is increased. After another 20 seconds the speed of the combustion and heating air fan is continuously increased within 17 seconds
to full load for full heat.
NOTE
This operating condition is omitted if the set temperature
(control idle) has already been achieved once.
The glow plug is deactivated and heating operation commences. A flame-out during speed up control causes a
restart, 5 restarts an error lockout of the heater.
Fuel Operated Heaters
With the glow plug activated the operating speed of the
combustion and heating air fan is continuously increased
within 4 seconds to full load for full heat. This operating
condition will be omitted if the start occurs after a control
idle period.
The glow plug is deactivated and heating operation commences. A flame-out during speed up control causes a
restart, 5 restarts an error lockout of the heater.
301
3 Functional Description
Air Top 2000 S
3.1.4 Heating Operation
During operation the combustion exhaust gasses flow
through the heat exchanger charging its walls with combustion heat, which in turn is taken up by the heating air
delivered by the heating air fan to be routed to the vehicle interior.
The temperature of the heating air sucked in is
measured by means of a temperature sensor fitted to
the air intake side of the air heater or by means of an externally located temperature sensor.
A temperature below the one set with the control element increases the heater performance up to maximum
heat. In order to extend the burner idle period of Diesel
operated heaters during permanent operation with a
heating performance in excess of 1.1 kW, the fuel dosing pump delivery rate is reduced every 15 minutes for
20 seconds.
A heating performance less than 1.1 kW causes the fuel
delivery to the dosing pump to be interrupted every 30
minutes for 4 seconds. Additionaly heating operation is
briefly suspended every 9 hours like in control idle. For
Diesel-operated heaters this is only applicable, if at this
time heating performance is less than 1.1 kW.
3.1.5 Control Operation
3.1.7 Switch-Off
Switching the heater off extinguishes the operation indication of the control element.
If no fuel has been delivered or if the air heater is in control idle, the air heater is deactivated immediately
without run-down.
If fuel supply has commenced it will be immediately
stopped at switch-off. Fan speed remains constant and
then decreases within 30 seconds to approx. 60% of full
speed. After this or with the flame sensor detecting “no
flame”, fan speed rises to maximum speed for 60 seconds and run down for 120 seconds is initiated. Rundown is at approx. 60% of full speed and is deactivated
automatically.
NOTE
Re-activation of the heater during run-down is permitted.
Run-down will be completed first with a subsequent restart.
3.1.8 Switch-off upon Failure
The control unit recognizes failures of individual air
heater components and malfunctions in the start sequence and in normal operation.
During control operation fan speed and dosing pump
rate of delivery are subject to heating performance.
The glow plug is deactivated.
3.1.6 Control Idle
After reaching the temperature set with the control element, heating performance is controlled to decrease.
The speed of the combustion and heating air fan slows
down and the fuel delivery rate to the dosing pump is reduced. When exceeding the air intake temperature set
with the control element during minimum heating performance, the dosing pump is deactivated after 5 seconds
and combustion terminates.
Fan speed remains constant for 35 seconds and is then
increased to approx. 60% of full speed for cooling the
heater down. the fan then continues to operate at approx. 30% of full speed until temperature is below the
temperature set with the control element. If temperature
falls below the one set with the control element, the
heater will restart (without break away).
NOTE
New settings on the control element are executed by the
control unit/heater with a time delay.
The air heater is deactivated and enters the error lock
out mode under the following conditions:
flame sensor open or short circuit
temperature sensor open or short circuit
glow plug open or short circuit
fan motor open or short circuit or fan speed wrong
dosing pump open or short circuit
overheating
low voltage below 10 Volt or high voltage above
15 Volt in excess of 20 seconds for 12 Volt heaters
low voltage below 20 Volt or high voltage above
30 Volt in excess of 20 seconds for 24 Volt heaters
A switch-off like in “switch-off” will be performed.
In case of overheating there will be no fuel supply. After
run-down the control unit is in the error lockout mode.
The operation indication outputs a flash code.
For error unlock the air heater has to be switched off
momentarily (at least 2 seconds) before switching on.
302
Air Top 2000 S
4 Technical Data
4. Technical Data
As long as no threshold values are given, the following
technical data are understood to include tolerances of
±10% usual for heaters at an ambient temperature of
+20 °C and at nominal voltage and conditions.
Electrical Components:
Control unit, combustion air fan, dosing pump, timer,
glow plug and control dial are for 12 or 24 Volts
operation.
The components temperature limiter and flame detector
are independent of voltage.
Air Heater Operation
Mark of conformity
Heater type
Fuel for Air Top 2000 S B (gasoline):
The fuel specified by the manufacturer must be used.
Fuel for Air Top 2000 S D (diesel/PME):
The diesel fuel specified by the vehicle manufacturer
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 approx. 15 minutes so that the fuel
system is filled with the new fuel.
The Air Top 2000 S D heater is also licensed for use with
PME (bio-diesel), which complies with ASTM D6751 and
DIN EN 14214.
AT 2000 S B
~ S 325
Air heater with evaporator burner
AT 2000 S D
~ S 324
Heat flow
Type of fuel
Fuel consumption
Nominal voltage
Operation voltage
Rated power consumption
Permitted ambient temp.:
Heater:
Dosing pump:
Control element:
Permitted combustion air
intake temperature
Setting range for
indoor temperature
- operation
- storage
- operation
- storage
- operation
- storage
Control range
Control range
Control range
Control range
1.1 – 2.0 kW
Gasoline
0.1 .. 0.2 kg/h (0.16..0.27 l/h)
12 Volt
10 … 15 Volt
-40 ° … +40 ° C
-40 ° … +85 ° C
-40 ° … +20 ° C
-40 ° … +85 ° C
-40 ° … +75 ° C
-40 ° … +85 ° C
-40 ... +20 °C
+10 ... +45 °C
0.9 – 2.0 kW
Diesel/Fuel oil (EL)
0.1 .. 0.21 kg/h (0.12 .. 0.24 l/h)
12 Volt
10 … 15 Volt
9 ...22 W
24 Volt
20 … 30 Volt
Volume flow of heating air
against 0.5 bar
CO
in exhaust
2
(perm. functional range)
Dimensions air heater
Weight, heater
Max.
Max.
9.5 … 10.5
3
70 m
/h
Length 311 ± 2 mm
Width 120 ± 1 mm
Height 121 ± 1 mm
2.6 kg
9.5 … 12.0
401
5 Troubleshooting
Air Top 2000 S
5. Troubleshooting
5.1 General
A malfunction of the Air Top 2000 S is indicated by an
error code displayed on the combination or standard
timer. When equipped with a standard control dial
the operating indicator flashes. In addition a heater check
out may be performed using a personal computer (refer
to operating instructions PC air heater diagnosis).
CAUTION
Troubleshooting requires profound knowledge about
structure and theory of operation of heater components
and may only be performed by skilled personnel.
In cases of doubt refer to Sections 2 or 3 for functional
interrelations.
CAUTION
Troubleshooting is normally limited to the isolation of
defective components.
The following causes for trouble are not considered and
should always be checked for to exclude them as cause
for trouble:
corrosion on connector
loose contact on connector
wrong crimping on connector
corrosion on electrical wiring and fuses
corrosion on battery terminals
If individual components are checked, the control unit
electrical connections must be disconnected.
After any correction of a failure a functional test has to
be performed in the vehicle.
5.2 General Failure Symptoms
The following table (Fig. 501) lists the possible failure
symptoms.
ydemeResuaC elbaborPmotpmyS eruliaF
Air heater switches No combustion after start or repeat Switch off heater momentarily and
off automat no hctiwstratsyllaci
Flame extinguishes during Switch off heater momentarily and
Operation indication flashes obstructions, allow heater to cool
down, switch off heater momentarily
and switch on
system voltage too low Switch off heater momentarily and
switch on
Heater expels black fumes Combustion air and/or Check combustion and exhaust
exhaust ducting blocked ducting for obstructions
Fig. 501 General Failure Symptoms
once again
no hctiwsnoitarepo
once again
once again
yrettab egrahClacirtcele elciheV
once again
rof gnitcud ria taeh kcehCstaehrevo retaeH
501
Air Top 2000 S
5 Troubleshooting
5.3 Failure Symptoms during Operation
The following table (Fig. 502) lists the possible failure
symptoms as they might occur during the functional
sequence of operation.
In case of malfunction the failure is to be isolated and
removed using this table. It is important to accurately
identify the failure symptom.
Should the failure symptom not be contained in this
table or the trouble not be detected under the specific
Failure Symptom shows after
....seconds
No start and no illumination immediately
of LED on control element
No start but LED illuminates immediately
Very low speed with no start immediately
failure symptom listed, in emergencies, assistance by our
service technicians may be requested.
NOTE
Overheating and dosing pump failure are always indicated additionally after run-down by the flashing LED of
the control dial.
In all cases of trouble also a defective control unit may
be the cause should all other components turn out to be
serviceable.
Possible Causes
Wrong cabling, defective fuse
Fan or control unit defective or fan blocked
Control idle operation: wrong manual control (selected
temperature is below air intake temperature) or wrong
integration (excessive air intake temperature)
Motor operates momentarily 1
and then stops
Stoppage without run-down 5
Run-down after 1
Run-down after 20
Run-down after 120
and dosing pump does not cycle
Run-down after 40 to 120
Run-down after 230
operation
Glow plug or flame sensor short or open circuit or
control unit defective
Fan motor obstructed, binding
Flame detection erroneous
Voltage to control unit too low
Cabling to dosing pump, pump itself or overheat
protection defective
Intermittent disconnect of connection to dosing pump
or to overheat protection
No flame: wrong fuel supply quantity, defective or slow
fan, coked burner (in particular pilot flame outlet bore),
combustion air/exhaust ducting obstructed or heat
exchanger coked, dosing pump seized
noitsubmoc gnirudnwod-nuR
Overheating or
voltage too low or
component error (flame sensor, glow plug,
overheat sensor, dosing pump, burner) or
no fuel supply or obstructed combustion air/exhaust
ducting
Stoppage without run-down during combustion
operation
Interruption of dosing pump during combustion
cycling and max. speed for operation
30 sec with subsequent re-start
Fig. 502 Failure Symptoms during Operation
Fan motor failure or seizure
Flame-out by gas bubbles in fuel delivery or strong
wind against exhaust outlet or defective no-flame
detection
502
5 Troubleshooting
5.4 Error Code Output
When equipped with a combination or standard timer a
malfunction will cause an error code output to the display of the timer for indication.
NOTE
When equipped with a control dial, the error code
output is indicated by flashing of the operating indicator/error code indication. The number of flash pulses
corresponds to the number indicated in the table below.
After a quick pulse train there will always be an error
code output.
Error code output on display of combination or
standard timer
F 01 No start (after 2 attempts)
Air Top 2000 S
F 02 Flame out (at least >5)
F 03 Voltage too low or too high
F 04 Premature flame detection
F 05 Flame sensor open or short circuit
F 06 Temperature sensor open or short circuit
F 07 Dosing pump open or short circuit
F 08 Fan motor open or short circuit or
wrong speed
F 09 Glow plug open or short circuit
F 10 Overheating
503
Air Top 2000 S
6 Functional Tests
6. Functional Tests
6.1 General
This section describes the on-vehicle and off-vehicle
testing of the air heater to check its proper operation.
WARNING
The air heater shall not be operated in enclosed areas
like garages or workshops not provided with exhaust
venting facilities.
6.2 Adjustments
6.2.1 Adjustment of the CO2 Contents
6.2.1.1 General
The CO
potentiometer on the control circuit board. The air heater
is preset by the manufacturer with respect to the combustion and heating air fan fitted. After adjustment by the
manufacturer the potentiometer is in center position
(Fig. 601). After an inadvertent loss of this position it is
sufficient to restore its original position.
The manufacturer setting may be corrected by rotating
the potentiometer. A suitable tool like a small screw
driver (2.5 mm tip) is to be used.
contents of the exhaust is adjusted with the
2
CAUTION
Set potentiometer slowly; observe end positions.
Adjustment may be performed at any electrical system
voltage.
Clockwise rotation increases the fan speed and decreases the CO
creases the fan speed and increases the CO
If the setting range is not sufficient (e.g. after replacement of the combustion and heating air fan) the manufacturer’s setting may be cancelled according to the
procedure described in the following.
6.2.1.2 New Basic Setting
The manufacturer’s setting cannot be restored.
1. Withdraw cover from upper shell according to 9.2.1.
2. Switch on air heater.
3. Rotate potentiometer two times and with no interrupt
through its complete setting range (e.g. max. - min.-
max.).
4. Adjust desired CO
5. Switch off air heater.
6. Install cover and secure.
contents. Counterclockwise rotation de-
2
contents.
2
CAUTION
contents (Fig. 601).
2
CO
2
+ –
Fig. 601 Adjustment of CO2 Contents
601
6 Functional Tests
6.3 Components Testing
CAUTION
During electrical testing always ensure that the control
unit and the component under test are electrically disconnected from each other.
6.3.1 Glow Plug Resistance Test
During electrical testing of the glow plug using a digital
multimeter, the following readings should be obtained:
Glow plug 12 Volt (red) 24 Volt (green)
Resistance at 25 °C: 0.324 ... 0.360 Ω 1.3 ... 1.44 Ω
Test current: < 5 mA < 5 mA
6.3.2 Flame Sensor Resistance Test
During electrical testing of the flame sensor using a digital multimeter, the following readings should be obtained:
Air Top 2000 S
Cold test:
Resistance at 25 °C: 2.6 ... 3.4 Ω
Test current: < 5 mA
Hot test:
Resistance at 800 - 1000 °C: 12 ... 15 Ω
(ceramic rod red hot over a length of approx. 20 mm)
Test current: < 5 mA
602
Air Top 2000 S
7. Circuit Diagrams
7.1 General
The air heater Air Top 2000 S may be operated
using the control dial (rated value transmitter/switch)
or with the control dial and a combination or
standard timer. The circuit diagrams (Figs. 702 to 704)
show the possible circuits 12 or 24 Volt with
control element
combination timer
control element and standard timer
Fig. 701 shows the terminal pin assignment.
7 Circuit Diagrams
X1 = Connection, Combustion and Heating Air Fan
X2 = Connection, Dosing Pump
X3 = Connection, Flame Sensor
X4 = Connection, Glow Plug
X5 = Connection, Temperature Limiter
Fig. 701 Terminal Pin Assignment, Air Top 2000 S
4X1X X3 5X2X
wolleyteloiv brown eulbkcalb
701
7 Circuit Diagrams
Connection X11/2 and X11/3
for TRS function only
2
Air Top 2000 S
? ?
?
A2 Control Unit
B1 Flame Sensor
B2 Temperature Sensor
B3 Temperature Limiter
E Glow Plug
M Motor
X8 Connection 2-pole
Y1 Dosing Pump
krameRerutalcnemoNmetI
0 S002 poT riAretaeH riA1A
4821 J EAS esuF talFA51 V21/A01 V42 esuF2F
noitacidni noitarepO)1S meti ni( neerg DEL1H
hctiwS gnitteS eulaV detaRtnemelE lortnoC1S
2A meti foelop-2 noitcennoC5X-1X
2A meti foelop-8 noitcennoC6X
S meti foelop-4 noitcennoC7X
Wire Gauges
Wire Colours
bl
br
ge
gn
gr
or
rt
sw
vi
ws
< 7.5 m 7.5 - 15 m
2
0.75 mm
1.0 mm
1.5 mm
2.5 mm
4.0 mm
blue
brown
yellow
green
grey
orange
red
black
violet
white
1.5 mm
2
1.5 mm
2
2.5 mm
2
4.0 mm
2
6.0 mm
2
2
2
2
2
2A meti foelop-2 noitcennoC9X
2A meti foelop-6 noitcennoC11X
2
)eriw-K( sisongaiDelop-1 noitcennoC21X
Fig. 702 Circuit Diagram Automatic Control Air Top 2000 S, 12V/24V with Control Dial
702
Air Top 2000 S
1
2
1
7 Circuit Diagrams
2
? ?
?
krameRerutalcnemoNmetI
0 S002 poT riAretaeH riA1A
A2 Control Unit
B1 Flame Sensor
B2 Temperature Sensor
B3 Temperature Limiter
E Glow Plug
4821 J EAS esuF talFA51 V21/A01 V42 esuF2F
standy indication,
operating indicator light
H8 Heating symbol in display (in item P) Operating indicator light,
overheat indication
noitanimulli lobmyS)P meti ni( thgiL9H
M Motor
P1 Combination Timer (1531)
2A meti foelop-2 noitcennoC5X-1X
2A meti foelop-8 noitcennoC6X
X8 Connection 2-pole
2A meti foelop-2 noitcennoC9X
2A meti foelop-6 noitcennoC11X
)eriw-K( sisongaiDelop-1 noitcennoC21X
P meti foelop-21 noitcennoC31X
Y1 Dosing Pump
Wire Gauges
< 7.5 m 7.5 - 15 m
2
0.75 mm
2
1.0 mm
2
1.5 mm
2
2.5 mm
2
4.0 mm
Wire Colours
,noitanimulli hctiws taeh tnatsnI)P meti ni( der DEL7H
bl
br
ge
gn
gr
or
rt
sw
vi
ws
lortnoc etomer gnitaeh tnatsnIhctiwS3S
blue
brown
yellow
green
grey
orange
red
black
violet
white
with plus from terminal (15/75)
to connection 10:
permanent operation during
instant heating as long as
ignition on
without plus to connection 10:
heating time programmable as
required (10 min to 120 min),
default setting 120 min.
Connection X11/2 and X11/3
for TRS function only
1.5 mm
1.5 mm
2.5 mm
4.0 mm
6.0 mm
2
2
2
2
2
Fig. 703 Circuit Diagram Automatic Control Air Top 2000 S, 12V/24V with Combination Timer
703
7 Circuit Diagrams
1
Air Top 2000 S
2
? ?
?
krameRerutalcnemoNmetI
0 S002 poT riAretaeH riA1A
A2 Control Unit
B1 Flame Sensor
B2 Temperature Sensor
B3 Temperature Limiter
E Glow Plug
4821 J EAS esuF talFA51 V21/A01 V42 esuF2F
standy indication,
operating indicator light
H8 Heating symbol in display (in item P) Operating indicator light,
overheat indication
noitanimulli lobmyS)P meti ni( thgiL9H
M Motor
P2 Standard timer
2A meti foelop-2 noitcennoC5X-1X
2A meti foelop-8 noitcennoC6X
1S meti foelop-4 noitcennoC7X
X8 Connection 2-pole
2A meti foelop-6 noitcennoC11X
)eriw-K( sisongaiDelop-1 noitcennoC21X
P meti foelop-21 noitcennoC31X
Y1 Dosing Pump
Wire Gauges
< 7.5 m 7.5 - 15 m
2
0.75 mm
2
1.0 mm
2
1.5 mm
2
2.5 mm
2
4.0 mm
Wire Colours
,noitanimulli hctiws taeh tnatsnI)P meti ni( der DEL7H
bl
br
ge
gn
gr
or
rt
sw
vi
ws
blue
brown
yellow
green
grey
orange
red
black
violet
white
1.5 mm
1.5 mm
2.5 mm
4.0 mm
6.0 mm
2
2
2
2
2
hctiwS gnitteS eulaV detaRtnemelE lortnoC1S
with plus from terminal (15/75)
lortnoc etomer gnitaeh tnatsnIhctiwS3S
1
to connection 10:
permanent operation during
instant heating as long as
ignition on
without plus to connection 10:
heating time programmable as
required (10 min to 120 min),
default setting 120 min.
Connection X11/2 and X11/3
2
for TRS function only
704
Fig. 704 Circuit Diagram Automatic Control Air Top 2000 S,
12V/24V with Control Dial and Standard Timer
Air Top 2000 S
7 Circuit Diagrams
12V
24V
3 2 1
6 5 4
9 8 7
Combination Timer 1531
Adapter Harness
P/N 9008440A
Grey
Lights (1)
(optional)
Black
Battery Positive
or Ignition Signal (10)
Red
Battery Positive (11)
Brown
Battery Negative (12, 4)
12 11 10
Fig. 705 Connection Diagram, Air Top 2000 S with Combination Timer
705
7 Circuit Diagrams
Air Top 2000 S
706
Air Top 2000 S
8 Servicing
8. Servicing
8.1 General
This section describes the servicing procedures that
may be performed with the air heater installed.
8.2 Work on the Air Heater
Prior to performing any work it is mandatory to disconnect the vehicle battery main lead. As long as the air
heater is in operation or in run-down, the battery main
supply must not be disconnected due to the danger of
overheating resulting in a response of the overheat protection.
When performing extensive repairs on the heater a complete removal is advisable. When performing repairs requiring a relocation of the installation position, the
relevant installation instructions and the vehicle-specific
installation proposal have to be observed.
8.3 Work on the Vehicle
For reasons of the air heater’s functional reliability perform the following servicing:
check heating air inlet and outlet for foreign matter
and contamination. (Contaminated or clogged heating air ducts may lead to overheating and thus
response of the temperature limiter).
Clean air heater exterior (prevent the ingress of
water).
Examine electrical connections for corrosion of contacts and for security.
Check combustion air and exhaust ducts for damage
and obstructions.
Check fuel lines and fuel filter for leakage.
Replace fuel filter if installed.
8.6 Visual Inspections and Installation
Regulations
8.6.1 Heating Air System
CAUTION
The integration of the air heater into the vehicle’s own air
system is not permitted due to the system’s high pressure and temperature.
CAUTION
In the vicinity of the air heater a temperature of 85 °C
must not be exceeded under any circumstances (e.g.
during body paint work).
8.4 Air Heater Test Run
WARNING
The air heater must not be operated, not even with
timer, in enclosed areas like garages or workshops not
equipped with an exhaust venting facility.
CAUTION
Operation of the heater without the control unit cover is
not permitted and causes overheating.
8.5 Servicing
NOTE
In order to avoid the seizure of mechanical components,
the air heater should be operated every 4 weeks for at
least 20 minutes.
The air heater does not require maintenance. It should
however be checked by Webasto-trained skilled personnel on regular intervals, the latest before the heating
season begins (point of time, when the heater is more
frequently in use due to weather conditions).
Fitted in the air heater on the heating air intake side is a
temperature sensor, which operates the heater in the
relevant range of performance in conjunction with the
control dial dependent on the air intake temperature
and position of the rated value transmitter. Heating performance is selected so that after quickly reaching the
preselected indoor temperature it is maintained at this
value. Air Top 2000 S heaters may be operated with an
external temperature sensor (see 9.1.2).
Minimum inside diameter of the heating air duct is
55 mm. Standard diameter is 60 mm.
NOTE
For heating air ducting only materials may be used
which are temperature-proof to at least 130 °C.
Maximum loss of pressure between suction and delivery
side of the heating air duct 1.0 mbar (10 mm water
column).
When exceeding this value the temperature limiter is
very likely to respond. The heating air hose is to be secured at its joints.
801
8 Servicing
8.6.2 Fuel Supply
The fuel is taken from the vehicle fuel tank or from a
separate fuel tank. The values for maximum pressure
at the fuel extraction point are shown in Fig. 801.
Air Top 2000 S
Permissible fuel inflow
height H
0.00 m (0.00 in.) 0.20 bar (2.9 PSI)
1.00 m (39.4 in.) 0.11 bar (1.6 PSI)
2.00 m (78.7 in.) 0.03 bar (0.44 PSI)
Maximum fuel intake
height S
0.00 m (0.00 in.) -0.10 bar (-1.45 PSI)
0.50 m (19.7 in.) -0.06 bar (-0.87 PSI)
1.00 m (39.4 in.) -0.02 bar (-0.29 PSI)
8.6.2.1 Fuel Tapping
Vehicles with a Diesel Engine
The fuel must be taken from the vehicle fuel tank or
from a separate tank (Figs. 802, 803 and 804). This
separate fuel pickup precludes any effect of pressure.
Vehicles with an Injection Engine
When installing the heater in a vehicle with fuel injection
systems, it is important to establish whether the fuel
pump is located inside or outside the tank.
At maximum pressure in
fuel line
At maximum negative
pressure in fuel tank
+
I
I
I
≤ 10 m (32.8 ft.)
I
1
2
≤ 1.2 m (3.9 ft.)
1
≤ 8.8 m (28.8 ft.)
2
max. 3m (9.8 ft.)
I
2
iØ2mm
iØ2mm
I
2
Fig. 801 Fuel Supply
iØ2mm
I
1
iØ2mm
I
1
H
S
If the fuel pump is located inside the tank, fuel can only
be extracted from the return line using a Webasto fuel
tee fitting in which case it must be ensured that the
return line continues almost to the bottom of the tank.
If this is not the case, a Webasto fuel standpipe
(see Figs. 802, 803 and 804) may be used.
If the fuel pump is installed outside the tank, the fuel
connection may also be made between the tank and
fuel pump, again using only the Webasto fuel tee fitting.
Vehicles with a Carburetor Engine
The fuel may only be extracted on cars using a special
Webasto fuel tee fitting as close to the tank as possible.
The connection may be made in either the supply or
return line, in which case the return line must lead
almost to the base of the tank. If this is not the case,
the return line may be extended.
The fuel tee must be fitted in such a way that any air or
gas bubbles are automatically discharged towards the
tank.
The fuel tee should not be located near the engine, as
gas bubbles may form in the lines on account of heat
radiated from the engine. This may cause problems
during combustion.
802
Air Top 2000 S
8 Servicing
Hole Pattern
25 mm (1 in.)
Fuel Tank Tap
Gaskets
Tank Fitting Plate
> 25 mm (> 1 in.)
Fig. 802 Webasto Fuel Tank Tap
* Use fuel tank tap only on metal fuel tanks
Plastic Tank
Gasket
Fig. 804 Fuel Tapping from Plastic Tank
(tapping via fitting plate)
NOTE
The fitting plate must be made of sheet metal!
8.6.2.2 Fuel Lines
Fuel lines may only be steel, copper, or plastic lines
made of unhardened, light and temperature stabilised
PA 11 or PA 12 ( e.g. Mecanyl RWTL) according to DIN
73378. As in most cases a permanently rising fuel line
routing cannot be ensured, the inner diameter must not
exceed a certain value. Starting from an inside diameter
of 4 mm, air or gas bubbles accumulate resulting in malfunctions should the lines be descending or have sags.
The diameters specified in Fig. 801 will ensure that
bubbles do not form.
Fig. 803 Fuel Tapping from Plastic Tank
(tapping via fuel drain plug)
A descending line routing from the dosing pump to the
heater should be avoided.
Loose fuel lines must be secured in order to avoid sagging. The installation must ensure protection against
stone impacts and undue temperatures (exhaust line).
The fuel line joints are to be secured against slipping
with hose clamps.
803
8 Servicing
Air Top 2000 S
Connection of 2 Pipes with Hose
The proper connection of fuel lines with hoses is shown
in Fig. 805.
Correct
Clamp
Wrong
Bubble
Fig. 805 Pipe/Hose Connection
Bubble
8.6.3 Dosing Pump
The dosing pump is a combined delivery, dosing, and
shut-off system and is subject to certain installation criteria (see Figs. 801 and 806).
8.6.3.1 Installation Location
It is advantageous to mount the dosing pump in a cool
location. The ambient temperature must never exceed
+20 °C during operation.
Dosing pump and fuel lines must not be installed in locations exposed to heat radiated by hot vehicle components. A heat shield is to be provided as required.
8.6.3.2 Installation and Attachment
The dosing pump is to be attached with anti-vibration
mounts. The installation location is limited according to
Fig. 806 to ensure sufficient self-venting capability. Due
to the danger of corrosion the plug connection between
dosing pump and dosing pump cable loom may only use
Webasto original parts.
8.6.4 Fuel Filter
Only a Webasto filter, P/N 50487171A, is allowed to be
used if the fuel is expected to be contaminated. Install
vertically if possible, however at most horizontally (check
flow direction).
AT 2000 S. 12 Volt and 24 Volt - Gasoline and Diesel
0-90°
0°
AT 2000 S D. 12 Volt and 24 Volt - Diesel DP 30
Installation Position only Horizontal
0-90°
0 - 90°
A
ø 5
Fig. 807 Fuel Filter
Fig. 806 Dosing Pump, Installation Position
and Attachment
804
Air Top 2000 S
8 Servicing
8.6.5 Combustion Air Supply
Combustion air must under no circumstances be extracted from rooms with persons. The combustion air
inlet must not point towards the forward direction of motion. It must be located so that no clogging by contamination is to be expected.
NOTE
For fuel operated heaters the combustion air tap must
be located in a possibly cool and splash water proof position using a combustion air line.
If the air heater is located in a closed installation box,
combustion air must be taken in from and the exhaust
routed to the exterior. The feedthroughs must not allow
exhaust fumes to enter the vehicle interior.
If a contamniated combustion air supply is expected, a
combustion air filter (Ident No. 21963A) can be fitted
(Air Top 2000 S D only).
8.6.6 Exhaust Line
Both lines must be routed away from the heater in a descending attitude. If this is not possible, a condensate
drain hole ø 4 mm must be provided at the lowest point.
Inner diameter of lines:
Combustion air line: 22 mm
Exhaust line: 22 mm
NOTE
When exceeding an exhaust line length of 2 m, insulated
exhaust lines have to be used (below minimum dew
point).
Smallest bending radius: 50 mm
In order to ensure the angle of 90° ± 10°, an attachment
is required not further than 150 mm away measured
from the exhaust pipe end.
Rigid pipes made of unalloyed or alloyed steel with a
minimum wall thickness of 1.0 mm have to be used as
exhaust line or flexible pipes made of alloyed steel only.
The exhaust pipe is secured to the air heater e.g. with a
clamp.
The exhaust muffler is preferably mounted near the air
heater. The direction of flow is optional.
ø 6,5
Fig. 808 Exhaust Muffler, Direction of Flow
Operation of the air heater is also permitted without
muffler.
8.6.7 Combustion Air Intake and Exhaust Lines
Exhaust exit direction
nearly vertical 90° ± 10°
10
°
Fig. 809 Exhaust Pipe Outlet, Installation Position
Any exhaust exit direction other than the one shown in
Fig. 809 may cause fires.
Sum of bends:
Combustion air line: max. 270°
Exhaust: max. 270°
°
10
WARNING
In order to avoid damage to the dosing pump cable, no
exhaust line may be used for the elongation of the combustion air intake line.
Length of the combustion air intake and exhaust line:
with muffler: max. 2.0 m
without muffler: max. 5.0 m
805
8 Servicing
Air Top 2000 S
8.6.8 Electrical Connections
8.6.8.1 Connection Air Heater, Control Dial
Electrical connection is according to Circuit Diagram
Automatic Control (see Section 7).
For connection of the cable loom the cover (see 9.2.1.1)
of the air heater has to be removed for connecting the
cable loom plug(s) to the control unit. Avoid touching the
control unit strip conductors.
Prior to first operation of the air heater the cover must be
fitted to avoid the loss of heated air (air heater overheating).
The cable feedthrough may be from left or right.
8.6.8.2 Connection of Power Supply
Ideally from the vehicle’s central electrical system.
An additional blade terminal fuse holder is to be
fitted to protect the heater and harness (supplied
with the heater). The fuse holder should be
installed as close as is practical to the power
source e.g. in the vehicle battery enclosure.
8.6.8.3 Connection Control Dial
The cable loom is prefabricated to connect to the control
dial (rated value transmitter).
For plug disconnection pull on terminal plug only
(Fig. 812).
By pulling on the cable loom the terminal plug is
secured (self-locking).
Fiber optic lens
(operation indicator)
Fig. 811 Control Dial
NOTE
The fiber optic lens must be in contact with the
rotary knob.
The fuse holder is constructed of weather resistant
components.
AT 2000 S
F = 15A (12V)
F = 10A (24V)
Fig. 810 Weather Resistant Fuse Holder
806
Fig. 812 Pulling the Plug
Air Top 2000 S
8 Servicing
1
5
4
3
2
6
7
Fig. 813 Example of an Installation
1 Control Dial
2 Air Heater
3 Dosing Pump and Damper
4 Fuel Filter (Accessory)
5 Fuel Connector
6 Exhaust Muffler
7 Fuse
807
8 Servicing
Air Top 2000 S
8.7 Removal and Installation
CAUTION
When the heater is installed it must not be dismantled.
8.7.1 Air Heater, Removal and Installation
8.7.1.1 Removal
1. Disconnect battery terminal leads.
2. Withdraw cover from upper housing shell according
to 9.2.1.
3. Disconnect the wire harness plug from control unit.
4. Disconnect interior air ducts if present.
5. Disconnect cable to dosing pump at cable disconnect.
6. Disconnect fuel inlet on air heater.
7. Disconnect connections of combustion air intake and
exhaust outlet on air heater.
8. Remove four nuts and lock washers on air heater.
9. Remove air heater and discard gasket.
8.7.1.2 Installation
1. Locate air heater with new gasket in installation
position and secure with four nuts and lock washers
(use original Webasto nuts only).
2. Tighten nuts with 6 + 1 Nm.
3. Secure connection for fuel inlet on air heater.
4. Secure connections for combustion air inlet and exhaust outlet on air heater.
5. Route cable to dosing pump and connect to dosing
pump.
6. Connect wire harness to control unit.
7. Install cover and secure.
8. Reconnect battery terminal leads.
9. Install interior ducting if present.
10. Bleed fuel supply system (see 8.8).
8.8 Start-Up
After you have installed the heater, bleed the fuel supply
system carefully.
NOTE
As a result of the low fuel consumption the heater must
be switched on several times to fill the fuel line.
Conduct a trial of the heater to check all the connections
for leaks and to ensure that they are secure. If the
heater suffers a fault during operation, the fault must be
located and remedied.
808
Air Top 2000 S
9 Repair
9. Repair
9.1 General
This section describes the repairs that may be performed on the air heater Air Top 2000 S after it has
been removed from the vehicle.
Any further disassembly will void the warranty.
For reassembly, only components of the proper spare
parts and kits are to be used.
9.1.1 Work on Components after Disassembly
CAUTION
All gaskets located between disassembled components
as well as the exhaust outlet seal must always be replaced and discarded.
9.1.1.1 Cleaning
All components disassembled must be cleaned with
cleaning spirit and subsequently dried with pressurized air.
All sealing compound must be carefully removed
from components using a suitable tool.
9.1.1.2 Visual Inspection
Examine all components for damages (cracks, deformation, wear, etc.) and replace as necessary.
Examine connectors and wiring for corrosion, loose
contacts, wrong crimping, etc. and repair as necessary.
Check terminals for corrosion and contacts for
security. Repair as required.
9.1.2.1 Installation of an External Temperature
Sensor
General
The heater can control the required temperature
perfectly if its temperature sensor is exposed to the air of
the main area of the vehicle. In certain circumstances,
this is not always possible using the temperature sensor
integrated in the control unit due to the installation
circumstances (addition of fresh air). In this case proper
temperature control can be ensured using an external
temperature sensor fitted in the appropriate area.
Procedure
1. Select adequate installation location for external
temperature sensor.
IMPORTANT
Temperature sensor should not be in the direct
line of heated air flow or located in the vicinity of
heating sources (e.g. vehicle’s own heater).
The sensor is to be installed at medium height
in the vehicle interior on surfaces that are as
vertical as possible.
The installation location should not be exposed to
direct sun light.
Do not mount temperature sensor behind curtains or
the like.
2. Mount external temperature sensor and route cable
to control unit.
3. Connect connector X9 and install cover.
4. Perform test run and check control behaviour.
9.1.2 Incorporation of Modifications
NOTE
The continous design improvement of the heaters is intended to optimise their serviceability avoiding failures or
malfunctions.
In general equipment in service may be retrofitted with
available modification kits. In the following that modification which may be incorporated easily during maintenace:
installation of an external temperature sensor for
optimising temperature control of the Air Top 2000 S
(see 9.1.2.1).
External
Temperature Sensor
Control Unit
X9
Cover
Connector X9
901
9 Repair
Air Top 2000 S
9.2 Disassembly and Assembly
9.2.1 Removal of Housing Components/Covers
9.2.1.1 Cover for Electrical Connection
Dependent on the type of installation the cable loom
exits the air heater either on the left or right.
The cover (1, Fig. 901) may be levered off using a blunt
blade in the areas marked
9.2.1.2 Grates for Heating Air Inlet and Outlet
The grates (5, Fig. 901) can be released from the
covers by twisting and pulling off forwards.
X .
1
9.2.1.3 Covers for Heating Air Inlet and Outlet
Both covers (3 and 6, Fig. 901) can be released and
removed by pressing the four detents on top and bottom
using a suitable tool.
9.2.1.4 Upper Housing Shell
NOTE
The covers for the heating air inlet and outlet must be
removed.
The upper shell (2, Fig. 901) can be raised by pulling up.
9.2.1.5 Lower Housing Shell
By gently pulling the lower shell (4, Fig. 901) on both
sides in the areas , you can release the fixing and
the shell can be taken off the motor casing.
Y
1 Cover, Electrical Connection
2 Upper Housing Shell
3 Cover, Heating Air Outlet
4 Lower Housing Shell
5 Grates
6 Cover, Heating Air Inlet
6
5
2
3
5
X
X
4
Y
902
Y
Fig. 901 Removal of Housing Components/Covers
Air Top 2000 S
9 Repair
9.2.2 Replacement of Control Unit
9.2.2.1 Removal
During removal avoid the build-up of static charge (i.e.
do not touch strip conductors).
1. Remove heater from vehicle (see 8.7.1.1).
2. Remove covers for heating air inlet and outlet
(6 and 3, Fig. 901) according to 9.2.1.3.
3. Remove upper housing shell according to 9.2.1.4.
4. Disconnect terminal connections (1, Fig. 902).
5. Remove screws (3) and remove control unit (2)
with bracket (6).
6. Remove screw (7) to separate control unit (2)
from bracket (6) if necessary.
7. Perform work on components after disassembly
(see 9.1.1).
9.2.2.2 Installation
NOTE
During installation avoid the build-up of static charge (i.e.
do not touch strip conductors).
9.2.3 Replacement of Temperature Limiter
9.2.3.1 Removal
1. Remove heater from vehicle (see 8.7.1.1).
2. Remove covers for heating air inlet and outlet
(6 and 3, Fig. 901) according to 9.2.1.3.
3. Remove upper housing shell according to 9.2.1.4.
4. Disconnect plug connection (blue) from terminal.
5. Remove screws (4, Fig. 902).
6. Remove temperature limiter (5).
7. Perform work on components after disassembly
(see 9.1.1).
9.2.3.2 Installation
1. Place temperature limiter (5, Fig. 902) into
installation position and secure with screws (4).
Ensure limiter is properly seated.
2. Torque screws to 1.5 ± 0.15 Nm.
3. Connect plug connections (blue) to terminal.
4. Install on upper housing shell and fix in position.
5. Slide on covers for heating air inlet and outlet and fix
in position.
6. Install heater (see 8.7.1.2).
1. Place control unit (2, Fig. 902) in position on
bracket (6) and secure with screw (7).
2. Place control unit (2) with bracket (6) in installation
position and secure with screws (3).
Torque screws to 0.7 ± 0.07 Nm.
3. Connect plug connections to terminal (Fig. 701).
4. Install upper housing shell and fix in position.
5. Slide on covers for heating air inlet and outlet and fix
in position.
6. Install heater (see 8.7.1.2).
7. Check CO2 setting and if necessary, adjust (see 6.2)
903
9 Repair
2
Air Top 2000 S
1
3
X6
4
5
7
6
1 Plug Connections
2 Control Unit
3 Screw (2)
4 Screw (2)
5 Temperature Limiter
6 Bracket
7 Screw
904
Fig. 902 Replacement of Control Unit and Temperature Limiter
Air Top 2000 S
9 Repair
1
1 Insulation
2 Seal
Fig. 903 Replacement of Combustion Air Fan (Disassembly)
9.2.4 Replacement of Combustion Air Fan
9.2.4.1 Removal
1. Remove air heater (see 8.7.1.1).
2. Remove control unit (see 9.2.2.1).
3. Remove seal (2 Fig. 903) from lower housing shell
and discard.
4. Remove air heater from lower housing shell.
!
MAX.
2
5. Remove insulation (1, Fig. 903)
6. Remove screws (1, Fig. 904).
7. Withdraw combustion air fan (3) and remove gasket
(2).
8. Perform work on components after disassembly (see
9.1.1).
905
9 Repair
Before assembly always
renew gasket.
Air Top 2000 S
9.2.4.2 Installation
1. Ensure that sealing surfaces on combustion air fan
and on heat exchanger are not damaged.
2. Place new gasket (2, Fig. 904) onto flange of
combustion air fan (3).
3. Place combustion air fan into assembly position and
mount using screws (1). Torque screws (1) to 6 Nm.
CAUTION
To ensure the proper function of the heater and to
prevent malfunctions of the temperature sensor,
the following must be observed when installing the
wire insulating mesh:
• The wire insulating mesh must be installed as
shown in Fig. 903 to prevent unwanted contact
with the temperature sensor terminals.
• Loose wire strands of the mesh must be cut off
to prevent contact with the temperature sensor.
• Ensure a secure fit between the heat exchanger,
insulating mesh, and the upper housing.
• An overly worn, damaged or flattened insulating
mesh must be replaced with a new mesh.
4. Place wire insulating mesh into position on the
heat exchanger (1, Fig. 903).
5. While slightly spreading the lower housing shell,
place over heat exchanger until guide slots
engage with pins on fan housing.
6. Fit new seal (2, Fig. 903) on heater mount base.
7. Install control unit (see 9.2.2.2).
8. Install upper housing shell, air inlet and air outlet.
9. Install air heater (see 8.7.1.2).
10. Check CO2 setting and adjust as required (see 6.2).
1 Screw (5)
2 Gasket
3 Combustion Air Fan
1
2
Combustion air fan must not be
disassembled any further
906
3
Fig. 904 Replacement of Combustion Air Fan (Assembly)
Air Top 2000 S
9 Repair
9.2.5 Replacement of Flame Sensor
9.2.5.1 Removal
1. Remove air heater (see 8.7.1.1).
2. Remove control unit (see 9.2.2.1).
3. Remove combustion air fan (see 9.2.4.1).
4. Remove screws (3, Fig. 905) and spoiler (2) for
cable protection.
5. Push out cable grommet (10) towards inside.
6. Carefully bend up locking tab (4) and withdraw flame
sensor (1) from burner insert (5).
7. Remove flame sensor.
8. Perform work on components after disassembly
(see 9.1.1).
9.2.5.2 Installation
CAUTION
Route cable of flame sensor below fuel pipe.
1. Pass flame sensor (1, Fig. 905) below fuel pipe, feed
connector through opening and push in cable grommet (10).
2. Feed cable with protection sleeve through locking tab
and insert flame sensor (1) into burner insert (5).
3. Squeeze locking tab (4).
4. Secure burner insert (5) with four screws (3) and fit
spoiler (2) for cable protection.
5. Pull cable of flame sensor tight.
6. Torque all 4 screws (3) to 6 ± 0.6 Nm.
7. Mount combustion air fan (see 9.2.4.2).
8. Install control unit (see 9.2.2.2).
9. Install air heater (see 8.7.1.2).
9.2.6 Replacement of Glow Plug
9.2.6.1 Removal
1. Remove air heater (see 8.7.1.1).
2. Remove control unit (see 9.2.2.1).
3. Remove combustion air fan (see 9.2.4.1).
4. Push out cable grommets (9 and 10, Fig. 905)
towards inside.
5. Remove four screws (3) and spoiler (2).
6. Tilt and withdraw burner insert (5) carefully.
NOTE
Ensure that burner insert (5) has separated from burner
tube (6).
CAUTION
The glow plug has to be pulled out with utmost care and
must under no circumstances be twisted (danger of
breaking). After a long period of combustion operation
the glow plug may be caked by fuel deposits. In this
case allow penetrating oil to react long enough to free
glow plug for removal.
7. Loosen screw (13) and remove glow plug (11)
from burner insert.
8. Perform work on components after disassembly (see
9.1.1).
9.2.6.2 Installation
1. Insert new gasket (7, Fig. 905) into heat exchanger
and place combustion tube (6) in assembly position.
2. Ensure that starting air bore is not clogged. If required
clean with wire (approx. 1 mm ø) (see Detail A).
CAUTION
During glow plug installation observe twist lock (see Detail B). That means that the glow has to be inserted so
that the contacts point towards the heat exchanger.
Otherwise there will be the danger of a short circuit.
3. Feed glow plug (11) into burner insert (5) and arrange
cable protective sleeve in slot of burner insert.
CAUTION
When performing the following step ensure that glow
plug is inserted in burner insert fully against stop.
4. Secure glow plug (11) with screw (13). Torque screw
(13) to 0.5 Nm.
5. Locate burner insert (5) in heat exchanger (8) observing that cable of flame sensor is positioned below
fuel pipe.
6. Feed connectors of glow plug and flame sensor
through openings and push in cable grommets (9
and 10).
CAUTION
When performing the following step ensure that there is
a tight fit between grommet (12) and heat exchanger (8).
7. Secure burner insert (5) using screws (3) and attach
spoiler (2). Torque screws (3) to 4 Nm.
8. Mount combustion air fan (see 9.2.4.2).
9. Install control unit (see 9.2.2.2).
10. Install air heater (see 8.7.1.2).
907
9 Repair
6
Air Top 2000 S
8
7
9
1 Flame Sensor
2 Spoiler
3 Screw (4)
4 Locking Tab
5 Burner Insert
6 Combustion Tube
7 Gasket
8 Heat Exchanger
9 Cable Grommet
10 Cable Grommet
11 Glow Plug
12 Grommet
13 Screw
10
11
4
3
2
1
5
13
12
908
Fig. 905 Disassembly of Heat Exchanger (Sheet 1 of 2)
Air Top 2000 S
Twist Lock
Detail A
9 Repair
Starting Air Bore
Detail B
Fig. 906 Disassembly of Heat Exchanger (Sheet 2 of 2)
909
9 Repair
9.2.7 Replacement of Burner Insert,
Combustion Tube, and Heat Exchanger
CAUTION
If the heat exchanger is going to be replaced, the
temperature limiter must also be replaced.
9.2.7.1 Removal
1. Remove air heater (see 8.7.1.1).
2. Remove control unit (see 9.2.2.1).
3. Remove combustion air fan (see 9.2.4.1).
4. Remove flame sensor (see 9.2.5.1).
5. Remove glow plug (see 9.2.6.1).
CAUTION
When performing the following step ensure that fuel
connection is not bent.
6. Remove burner insert (5, Fig. 905).
7. Withdraw combustion tube (6) from heat exchanger
(8) and remove gasket.
8. Perform work on components after disassembly (see
9.1.1).
Air Top 2000 S
9.2.7.2 Installation
1. In case a new heat exchanger is fitted, secure
temperature limiter (5, Fig. 902) with screws (4).
Torque screws to 1.5 ± 0.15 Nm.
2. Fit new gasket (7, Fig. 905).
3. Bring combustion tube (6) in assembly position.
NOTE
The burner insert will be secured when installing flame
sensor and glow plug.
CAUTION
When performing the following step ensure that the fuel
connection is not bent.
4. Install glow plug (see 9.2.6.2).
5. Install flame sensor (see 9.2.5.2).
6. Mount combustion air fan (see 9.2.4.2).
7. Install control unit (see 9.2.2.2).
8. Install air heater (see 8.7.1.2).
910
Air Top 2000 S
10. Packaging/Storage and Shipping
10.1 General
When it is necessary to ship the heater and its components
to a Webasto repair center for inspection or repair, they
are to be cleaned and packaged so that they are protected
against damage during handling, transportation, and
storage.
In storage an ambient temperature of +85 °C and -40 °C
must not be exceeded.
10 Packaging/Storage and Shipping
06/2008 1001
Notes
Air Top 2000 S
Org. 06/2008 Rev. N/A P/N LIT9000557A © 2008 Webasto Product N.A., Inc.
WEBASTO PRODUCT N.A., INC.
15083 North Road
Fenton, MI 48430
Technical Assistance Hotline
USA: (800) 860-7866
Canada: (800) 667-8900
www.techwebasto.com
www.webasto.us
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