autoterm AIR-2D 12V/24V Air Heaters User Manual
- October 27, 2023
- Autoterm
Table of Contents
autoterm AIR-2D 12V/24V Air Heaters User Manual
EN
Repair Manual
Air heaters
AIR-2D 12V/24V AIR-4D 12V/24V AIR-8D 12V/24V AIR-9D 12V/24V
Manufacturer: AUTOTERM LLC Paleju 72, Marupe, Latvia, LV-2167 Warranty
Department [email protected] Technical Support [email protected]
www.autoterm.com
v11.2017
Table of Contents
1 Technical Specifications ……………………………………………………………………………………… 4 2 Safety
…………………………………………………………………………………………………………………. 5 3 Troubleshooting.
………………………………………………………………………………………………… 5 4 Heater Dismounting and Disassembly.
………………………………………………………………. 11 5 Heater Components – Repair and Replacement.
………………………………………………… 14
5.1 Functions, Removal and Replacement of Glow Plug…………………………………………. 14 5.2
Functions, Removal and Replacement of Glow Plug Screen ………………………………. 15 5.3
Functions, Removal and Replacement of Overheat Sensor. ……………………………….. 16 5.4
Functions, Removal and Replacement of Temperature Sensors (AIR-8)……………… 19 5.5
Functions, Removal and Replacement of Flame Indicator. ……………………………….. 20 5.6
Functions, Removal and Replacement of Air Blower. ………………………………………. 21 5.7
Functions, Removal and Replacement of Control Unit. …………………………………….. 22 5.8
Functions, Removal and Replacement of Combustion Chamber………………………… 23 5.9
Functions, Removal and Replacement of Heat Exchanger. ……………………………….. 25 5.10
Functions, Removal and Replacement of Fuel Pump. ……………………………………….. 25 5.11
Functions, Removal and Replacement of Controller. ……………………………………….. 26 5.12
Functions, Troubleshooting and Replacement of Cabin Sensor (it is available as
an option) …………………………………………………………………………………………………………………. 27 6 Tools and
Equipment for Maintenance and Repairs. …………………………………………. 28 7 Heater Check
after Repair………………………………………………………………………………… 29
2
This Repair Manual is intended for service personnel performing maintenance
and repairs of Air heaters (hereinafter – “the heater”) and their
modifications. It describes methods of determining possible faults, how to
determine the working condition of components and parts, and how to identify
the need to replace them.
The Manual provides basic technical data, descriptions of components, their
functions as parts of the heater, recommendations for their maintenance and
repair, main distinctions of different models.
Principles of operation, main parts and components of the standard air heater
are described in CPAU (the catalog of parts and assembly units).
Electrical diagram of the air heater is provided in the Operation Manual. When
repairing the heater, its Operation Manual and the catalog of parts and
assembly units should be referred. Repair Manual may not reflect minor design
changes made by the manufacturer. Abbreviations used in this Manual: CU
Control Unit; CC Combustion Chamber; AB Air Blower; CNTRL Controller; FP
Fuel Pump; VEH Vehicle.
3
1 Technical Specifications
Table 1shows the Technical Specifications of the heater. The Specifications
are given with the tolerance of 10%, obtained at 20 and rated voltage.
Table 1
Rated voltage, V Fuel
AIR
2D
4D
4D
8D
12 / 24 12 / 24 12 / 24
12
24
diesel fuel depending on ambient temperature
Heating output, kW, at max / min mode: 2 / 0,8
3 / 1
4 / 1
6 / 3,2 7,5 /3,2
Hot air flow, m3/hr., at max / min mode:
75 / 34 120 / 70 120 / 70 175 / 70 235 / 70
Fuel consumption, l/hr., at max / min mode:
0,24 / 0,1 0,37 / 0,1 0,51 / 0,12 0,76 / 0,42 0,9 / 0,42
Power consumption, W, at max / min mode:
29 / 10 46 / 10 57 / 10
75 / 8
90 / 9
4
2 Safety 2.1. Repairs should be conducted in compliance with applicable
occupational safety instructions. 2.2. Violation of the rules of operation of
the air heater may cause a fire. 2.3. The workplace should be provided with
fire-fighting implements. 2.4. Do not refuel when operating the heater. 2.5.
Do not operate the heater in enclosed spaces and in areas with poor
ventilation. 2.6. Do NOT disconnect the heater from the power supply before
the end of the purge cycle. 2.7. In case of flame at the outlet of the exhaust
pipe, the heater should be turned off and after it is stopped, troubleshooting
can be started. 2.8. Do not connect or disconnect electrical connectors of the
heater when the power is ON.
3 Troubleshooting. During operation, the air heater may malfunction. A
malfunction is identified by the
code displayed on the controller panel, see Table 2 for code descriptions.
Other malfunctions are possible, which are not identified by the control unit.
For
instance, loss of tightness of the heat exchanger (burn-out), or burn-out
gaskets, or a decrease in heat output as a result of carbon formation inside
heat exchanger. These faults can be detected visually.
DO NOT USE THE HEAT EXCHANGER IF IT LOSES ITS TIGHTNESS. During operation of
the air heater, failures of individual elements of the heater may occur, which
can be replaced without removing the heater from the vehicle (e.g.:
replacement of the fuel pump; glow plug, controller). Attention! In September
2015, a standardization of fault codes was carried out, as a result some codes
were changed.
5
Table 2
Fault Code
Description
Overheating of 01 the heat
exchanger
Possible overheating at the intake temperature 02 sensor. Sensor temperature
(control unit) is more than 55 degrees.
Fault Cause
The sensor sends a signal to shut down the heater. Heat exchanger temperature
in the sensor zone is over 250°C
Recommended Solutions
Check the intake and outlet of the heating unit for unobstructed entry and
exit of heated air. Check the integrity of the fan and its performance. Check
the temperature sensor and replace it if necessary. (see items 5.3 – 5.4)
Inspect the heat exchanger. Check and remove carbon deposits from the inside
of the heat exchanger, if necessary (see items 5.8 – 5.9)
Control unit is insufficiently cooled down during 5 min. purging before startup; or overheating of the control unit during operation.
Check the intake and outlet of the heating unit for unobstructed entry and exit of air and re-start the heater to cool it down. Replace the control unit. (see item 5.7)
05
Faulty temperature sensor (AIR2D) or flame indicator
Short circuit to the casing or open circuit in the wiring of the sensor.
Check sensor as in 5.3 or 5.5, replace if necessary
04 or 06
Faulty temperature sensor in the control unit
Temperature sensor out of
order (located in the control unit, cannot be replaced)
Replace control unit (see item 5.7)
Overheat 07 sensor – open
circuit
08
09
Faulty glow plug
Faulty sensor. Oxidation Check overheat sensor circuit for
of contacts in the terminal an open. Remove oxidation from
block.
the connector contacts.
See Fault Code 29.
Short circuit, open circuit, faulty control unit.
Check glow plug, replace if necessary. (see item 5.1) Check the control unit, replace if necessary. (see item 5.7)
6
Continuation of table 2
Fault Code
Description
Fault Cause
Recommended Solutions
Increased friction in the
Electric motor of bearings or contact
10
the air blower does between the impeller
not develop the
and fan shroud in the
necessary speed. blower.
Check electric motor, if possible correct the fault; replace air blower if necessary (see item 5.6).
Faulty electric motor.
Faulty air
Mechanical fault.
11
temperature sensor Oxidation of contacts in Check connecting wires.
(intake) only for the block.
Check sensor (item 5.4).
AIR-8D.
Shut down,
overvoltage more
12 than 30V (for 24V)
or more than 16V
(for 12V).
Faulty voltage
regulator.
Shut down, low
Faulty battery.
voltage, less than
15
20V (for 24V) or less than 10V
(for 12V)
Check battery terminals and wiring. Check the battery, charge it or replace if necessary.
The heater does
13
not start – two automatic start
attempts failed.
No fuel in the tank
Fuel grade does not match the operating conditions at low temperatures.
Insufficient supply of fuel.
Fill the fuel tank.
Replace fuel, see Operation Manual.
Eliminate fuel line leakage or blockage. Check the performance of the fuel
pump, replace if necessary (see item 5.10).
Clogged exhaust duct or Clean air intake or exhaust duct combustion air intake. of possible clogging.
7
Continuation of table 2
Fault Code
13
16
Description
The heater does not start – two automatic start attempts failed.
During the purge time, temperature sensor was not cooled down. Time for
ventilation was exceeded.
Fault Cause
Recommended Solutions
Insufficient preheating of the glow plug, faulty control
Check the plug, replace if necessary (see item 5.1). Check voltage supplied by control unit,
unit.
replace if necessary.
The impeller touches the
the fan shroud in the blower, and, as a result, flow of air into the combustion
Replace blower after determining its malfunction. (see item 5.6).
chamber is reduced .
The glow plug housing
in CC is clogged.
Clean the glow plug hole.
Clogged glow plug
Replace the glow plug screen, if
screen or it is not
needed, and install it in
installed all the way accordance with item 5.2.
into housing.
During 5 min purge before startup, temperature sensor was not sufficiently cooled.
Check the intake and output of the heater for unobstructed entry and exit of air. Check the integrity of the fan and its operation. Check the sensor, replace if necessary.
Check the wiring of the fuel
Short circuit or open pump for short circuit and open
17 Faulty fuel pump circuit in the wiring
circuit.
of the fuel pump.
Check the wires to overheat sensor,
insulation integrity.
Burnt out fuses on the power harness.
Check the fuses and replace if necessary.
No communication
Check the connectors and the green
20
Heater does not start between the controller and the control unit.
wire in the connecting harness. Remove oxidation from connectors. Check the controller and the
Controller receives no data from the control unit.
connecting harness, replace if necessary. If the controller is operational, replace the control unit.
8
Continuation of table 2
Fault Code
Description
Fault Cause
Recommended Solutions
27
Motor does not rotate
Damaged bearing or rotor, foreign objects, etc.
Check connectors and wiring leading to the electric motor board and the control unit. Eliminate the fault, if possible. (see item 5.6)
28
Motor rotates. Speed is not regulated.
Faulty electric motor control board or heater CU.
Replace air blower.
08 or 29
Flame failure during operation of the heater.
Insufficient fuel supply. Faulty fuel pump. Faulty flame indicator.
Check for leaks or clogging of fuel lines, tighten the clamps on the fuel lines. Check combustion air intake and exhaust pipe. Check the amount of fuel supplied by the fuel pump, and replace it if necessary. (see item 5.10) If the heater starts, check flame indicator and replace it if needed. (see items 5.3 or 5.5)
30
Heater does not start
No communication between the controller and the control unit.
Control unit receives no
Check connectors and white wire in the connecting harness. Remove oxidation of connectors. Check controller and connecting harness, replace if necessary. If controller is operational,
data from the controller.
replace control unit.
Overheating
of hot air
31
outlet temperature
sensor.
Air 8D
Hot air temperature sensor gives a signal to turn off the heater.
Check the temperature sensor (item 5.4) only AIR-8D
9
Continuation of table 2
Fault Code
Description
Fault Cause
Recommended Solutions
Faulty
32
temperature sensor at air
intake.
Faulty temperature sensor at air intake.
Check connecting wires. Check sensor (item 5.4). only AIR-8D
33
Heater control is blocked
Error “Overheating” repeated three times.
See instructions for unblocking the heater. only for AIR-8D
Wrong 34 component
assembly
One of the temperature sensors (intake, output or overheating) is installed in wrong location and gives wrong signal.
Check location of temperature sensors. Check sensors (item 5.4) only AIR-8D
35 Flame failure Supply voltage drop.
Check the battery, wiring. (Voltage drop may occur due to prolonged use of
electric starter)
only AIR-8D
36
Flame indicator temperature above normal
Faulty flame indicator. Malfunction of the stabilizer in combustion chamber.
Check flame indicator (item 5.5). Inspect combustion chamber. (item 5.8) only for AIR-8D
78
Flame failure during operation.
Air bubble in fuel system. Faulty fuel pump. Faulty flame indicator.
Check fuel lines for leaks or clogging. Tighten fuel line hose clamps. Check combustion air intake and exhaust duct.
10
4 Heater Dismounting and Disassembly.
Replacement or checking of the heater components requires its partial disassembly. Partial disassembly of the mounted heater is allowed, if there is an access to the dismounted components.
4.1. Dismounting and Disassembly of AIR-2D
– remove the heater from VEH;
– remove the upper and lower casings;
Casing should be removed as follows:
a) Remove clips. To remove clip, use screwdriver (with a thin tip) to pry the clip
out and slide it left or right for full release (Fig. 1);
b) Remove grids rotating them in either direction;
c) Remove upper and lower casing shells.
–
Upper Casing Clip
ProtrusiononCasing
Lower Casing
Fig.1- Removal of clips from casing .
– disconnect the contacts from the control unit (1 glow plug contacts, 2 –
sensor contacts, 3 – AB contacts);
air blower
control unit
harness
glow plug
Fig. 2 Heater.
11
sensor
– remove glow plug and bushing (use S=27 to hold bushing, and S=12 to turn glow plug out);
heat exchanger
plug bushing
gasket
Fig. 3 Plug with Installation Kit.
– remove secure screw of CU and dismount it; – remove screws fastening AB to
heat exchanger and disconnect AB; – remove screws fastening screen to CC,
remove screws fastening CC to heat exchanger,
remove CC;
4.2. Dismounting and Disassembly of AIR-4D
– remove heater from VEH; – remove fastening screws of the plug
cover, remove fastening screws of casing, remove casing halves; – disconnect
glow plug connector and other connectors from control unit; – remove fastening
screw of the control unit and dismount it; – remove glow plug from bushing and
turn bushing out; – remove screws fastening AB to the intermediate unit and
disconnect AB; – remove screws fastening the intermediate unit to the heat
exchanger (inside housing of the intermediate unit) and remove intermediate
unit; – remove screws fastening CC to heat exchanger.
glow plug cover
bushing
glow plug O-ring washer rubber bushing
Fig. 4 Glow plug with Installation Kit.
12
4.3. Dismounting and Disassembly of AIR-4D – remove heater from VEH; –
remove upper and lower casing shells (Fig.1); – disconnect contacts from CU,
remove fastening screw of CU, dismount it; – turn out glow plug; – remove
screws fastening AB to intermediate unit and dismount AB; – remove screws
fastening intermediate unit to heat exchanger and dismount
intermediate unit together with CC; – remove screws fastening CC to
intermediate unit.
4.4. Dismounting and Disassembly of AIR-8D – remove heater from VEH; –
remove fastening screws of glow plug cover and control unit; – disconnect all
contacts from CU, dismount CU; – remove fastening screws of casing halves,
dismount them; – remove glow plug cap, unscrew glow plug; – remove fastening
screw of AB from intermediate unit, dismount AB; – disconnect CC with
intermediate unit from heat exchanger (unscrew nuts on the
perimeter of intermediate unit); – remove screws fastening CC to intermediate
unit.
13
5 Heater Components – Repair and Replacement.
5.1 Functions, Removal and Replacement of Glow Plug.
The glow plug provides ignition of fuel mixture during start-up of the heater. Removal and replacement of glow plug is described in Section 5.
Model
Glow Plug Operating Voltage
Heater Operating Voltage
AIR-2D AIR-4D
9V
12V
18V
24V
AIR-8D
12V 12V
24V
Performance check instruction: Remove glow plug from the bushing, connect it to CU and start the heater. Note how glow plug heats up, it should start heating up from the tip to the middle of the heating element. If the heating element heats up from the middle or from the tip and to the base, then the glow plug is faulty. If the glow plug heats up insufficiently, check the voltage outputted by CU to the glow plug connector. The supply voltage should be 9, 12, 18V (depending on the model). If the voltage readings do not match, replace the CU. If after the replacement of the CU the heater is operational, the replaced CU is considered failed. If glow plug is not heating up, check its operation. To do this, disconnect glow plug connector and connect glow plug to DC power supply with voltage of 9, 12, or 18V (depending on glow plug model) and after 30 seconds, measure the current. Current should be between 5.2 to 6.78A (for 9V), from 3 to 5.2A (for 12V) and 2.5 to 3.4 (for 18V). Test time – no more than 90 seconds. Time between tests no less than 180 seconds. If glow plug does not meet any of the above requirements, it should be replaced. Glow plug replacement is performed in reverse order. Before installation, check O-rings for weariness. If glow plug is OK, check the wires and wire contacts on the control unit. If the contacts are clean, replace CU and repeat the start. If after replacing CU heater is operational, then replaced CU is considered failed and must be replaced.
14
5.2 Functions, Removal and Replacement of Glow Plug Screen
The screen is designed for uniform fuel supply to the CC. When replacing or
checking glow plug, it is necessary to check the screen for carbon deposits or
clogging. If there are carbon deposits, the screen should be replaced. In most
cases removed screens get damaged and are not re-usable. Install the screen
using mandrel (Fig. 6) according to Fig.5, all the way in (until the screen
touches the evaporator in the combustion chamber). Before installing
replacement screen into the housing (bushing) clean the hole “A” located on
the cylindrical surface of the glow plug housing (bushing). The hole in the
screen should be positioned at 45° away from the fuel tube.
heat exchanger
glow plug
O-ring
washer
glow plug bushing
bushing gasket
combustion chamber
screen
screen
sealing washer clamp
glow plug
protecting cap glow plug housing combustion chamber
screen
hole in glow plug housing of the combustion chamber Fig. 5. Installation of
Plug and Screen in the Fitting of the Combustion Chamber.
15
Ø17.7-0.05
Ø12.3-0. 1 Ø8.6-0.05
Ra 1.6
Ra 1.6
10±0.1 75.0
Ra 1.6
19±0.1
R2
1. MATERIAL STEEL 40XH GOST 4543-71 or similar
21. HRC45-50. 40 4543-71 … 2. RC 45……50
Fig. 6 – Mandrel Dimensions.
Attention! The screen should be installed with interference fit until it
stops. If the screen is not properly installed, the heater may malfunction
during start-ups.
DO NOT DRIVE SCREEN INTO HOUSING USING BUSHING OR GLOW PLUG.
5.3 Functions, Removal and Replacement of Overheat Sensor.
5.3.1 Bimetal overheat sensor. Overheat sensor (Figure 7) is used to control
the heating temperature of the heat
exchanger. If heat exchanger temperature exceeds 250°C the heater shuts down.
The overheat sensor requires replacement if the heater shuts down at heat
exchanger’s temperature below 250°C, or for the reasons set out in Table 2.
If you receive the error “Overheating” at starting or during operation, then:
- Check the integrity of sensor wire insulation. 2. Check overheat sensor
electrical contacts. 3. Check the temperature sensor for short circuit. In a
cool state (<250°C) the sensor is
closed and reads “short-circuit”. If this does not happen, replace the sensor. - Replace the overheat sensor and test the heater. If the heater is
operational with new
sensor, the replaced sensor should be considered faulty and disposed. 5. Check the CU. Connect overheat sensor wires (Figure 7a), start the heater.
– If there is an error “Overheating” the CU is faulty. Replace the CU. – If the heater is working properly – disconnect the closed wires. The control panel
should display the error “Overheating”. If the error does not appear – the CU is defective. Replace the CU.
Disassembly in accordance with section 4.
16
Fig.7 Overheat sensor.
Fig.7 Closed Wires.
Install replacement heat sensor in reverse order. Remove dirt or oil from contacts with a clean cloth soaked with degreaser. Upon detection oxidation on contacts, clean them with fine sandpaper, wash with degreaser, and tighten for proper connection.
5.3.2 Thermocouple overheat sensor . Since November 2015, heaters AIR-4D and
AIR-8D are equipped with
a thermocouple overheat sensor. AIR-2D has always been equipped with this
sensor.
The sensor is mounted on the heat exchanger and made in a form of ring with an
inbuilt thermocouple with two conductors. For heaters AIR-2D it performs the
functions of overheat sensor and flame indicator (Fig.8). During operation,
the sensor monitors the temperature of the heat exchanger. When heat exchanger
temperature goes exceeds 250°C, the heater shuts down automatically. The
sensor has to be replaced if the heater shuts down as described in Table 2.
Disassembly is performed according to Section 4. To dismount the sensor from
the heater, remove the lock washer and the sensor (Fig.8).
Installation replacement overheat sensor in reverse order. The lock washer
should be replaced with a new one.
lock washer bushing sensor washer
heat exchanger
Fig.8 Overheat Sensor (thermocouple)
17
Check the sensor for open circuit with a tester. If there is an open circuit
fault, the sensor is defective.
Check insulation resistance between the terminals and the housing. The
resistance should be not less than 100 MOhm at 100V. Ambient temperature
during resistance measurements must be between 15 and 35°C, relative humidity
less than 80%. If insulation resistance does not meet this requirement sensor
should be replaced.
Check the sensor terminal on the control unit. Install a jumper instead of the
sensor (Figure 9). If the heater starts with no fault code, the CU is OK. Turn
off the heater and remove the jumper.
If an error occurs during operation of the heater, it is possible that there
is a crack (open circuit fault) in the junction of the thermocouple sensor.
There are two methods to identify the problem: 1. Disconnect sensor from
control unit, connect sensor wires to the multimeter (to terminals of
temperature measurement) and heat the sensor with heat gun or lighter. The
temperature rise should be smooth. If the temperature changes suddenly, or it
shows the initial value, the sensor is damaged. In this case, after cooling,
the open circuit fault may disappear. 2. Disconnect the sensor from the
heater, and measure the voltage generated by the sensor when heated. When the
sensor is heated to +100°C (temperature of boiling water), the voltage should
be approximately 3 millivolts. The voltage on the terminal marked with red,
should be of positive polarity relative to the terminal marked with black.
Check the polarity of the sensor connection to the CU (wire with black marking
is connected to the connector terminal of the CU with a black dot). A magnet
can be used to check the correctness of marking. Contact of the wire with the
black mark is magnetic. If necessary, swap the terminals in the sensor
connector of the control unit.
In the case of an open circuit fault, sensor is defective and should be
replaced. To check the sensor terminal in the CU, install a jumper instead of
the sensor (Fig.9). – If the heater is started and there is no sensor fault,
the CU is OK. Remove the jumper and connect a working sensor. – If the problem
persists, replace the CU.
Fig. 9 Jumper.
Fig. 9 Connection.
18
Remove dirt and oil from the contacts with a clean cloth soaked in degreaser.
5.4 Functions, Removal and Replacement of Temperature Sensors (AIR-8D).
5.4.1 Since January 2015, AIR-8D heaters are equipped with a temperature
sensor for heated air.
The sensor is installed at the heated air outlet and is connected to the CU.
Disassembly is performed in accordance with Section 5.
Sensor performance (with power applied to the heater) can be determined by the
output voltage.
The output voltage at 0°C is 2,73V. Voltage increases with temperature. As
the temperature increases by 1°C, the output voltage will increase by 10mV.
Compare the room temperature and the corresponding voltage outputted by the
sensor.
If the sensor gives incorrect voltage, it is necessary to replace the sensor.
To avoid mistakes when evaluating performance of the sensor, it is necessary
to substitute it with a known-good. If the cause of heater failure is
eliminated with the installation of the new sensor, then the old sensor is
considered to be inoperable and has to be replaced. When replacing the
temperature sensor, installation is in the reverse sequence. If the problem
persists, replace the control unit to a known-good.
Plug
Temperature Sensor
Temperature Sensor
Overheat Sensor
Fig.10 Sensors.
5.4.2 From October 2015, heaters are equipped with an additional heated air
temperature sensor.
The sensor is checked as described in 5.4.1.
19
5.5 Functions, Removal and Replacement of Flame Indicator.
Flame indicator is used to monitor presence of flame in the combustion
chamber. It is a metal tube with a built-in thermocouple.
If an error is displayed when the heater is turned on, check the flame
indicator for continuity with a tester. If there is a break, the indicator is
defective and should be replaced;
Check the flame indicator channel of the control unit. For that, set a jumper
instead of the flame indicator (Figure 9). If the flame indicator fault code
is not displayed at the start of the heater, the CU is OK. Turn off the heater
and remove the jumper.
Check insulation resistance between the terminals and the indicator casing.
The resistance should be not less than 100 MOhm at a voltage of 100V. Ambient
temperature during resistance measurements should be between 15 and 35°C,
relative humidity less than 80%. If insulation resistance does not corresponds
to this requirement, it is necessary to replace the flame indicator.
If an error occurs during operation of the heater, it is possible that there
is a crack (open circuit fault) in the junction of the thermocouple of the
flame indicator. There are two methods to identify the problem:
1. Turn out the flame indicator, connect its contacts to the multimeter (to
the terminals of temperature measurement) and heat the sensor, for instance
with a cigarette lighter. The observed temperature rise should be smooth. If
the temperature changes suddenly, or assumes its initial value, the indicator
is damaged. In such a case, the open circuit fault may disappear after cooling
off of the indicator.
2. Turn out the flame indicator from the housing, and measure the voltage
generated by the indicator when heated. When the indicator casing is at +100°C
(temperature of boiling water), the voltage should be approximately 3
millivolts. The voltage on the terminal marked with a red tubing, should be of
positive polarity with respect to the terminal marked with a black tubing.
In the case of an open circuit fault, the flame indicator is defective and
should be replaced.
To avoid mistakes when evaluating performance of the flame indicator, it is
necessary to substitute it with a known-good. If the cause of the heater
failure is eliminated with the installation of a new flame indicator, then the
old flame indicator is considered to be inoperable and has to be replaced.
If the problem persists, check the polarity of the connection of the flame
indicator to the CU (wire with black marking is connected to the connector
terminal of the CU with a black dot, Fig. 7b). A magnet can be used to check
the correctness of wire marking. Contact of the wire with the black mark is
magnetic.
20
5.6 Functions, Removal and Replacement of Air Blower.
The blower (Fig.11) consists of an electric motor with a volute. The motor
shaft carries an impeller on the volute side (for air supply into the
combustion chamber), and a fan on the other side (for heated air supply).
Electric Motor with Volute
Fan
Impeller
AIR-2D
AIR-8D
Fig.11 Air Blower.
Rotating impeller generates air flow in the annular channel of the volute,
which enters the combustion chamber to ensure combustion, and also purges the
combustion chamber while cooling it and removing remaining fuel and moisture
before and after the combustion process.
The fan creates a flow of air that passes through the radiators of the heat
exchanger, when the heater is in operation, is heated, and the heated air
enters the vehicle cabin or other interior spaces of the vehicle.
Troubleshooting the air blower: 1) Check cleanliness of the contacts
connecting AB to CU; 2) Check the performance of the AB. To accomplish this,
briefly connect the terminal of the blue wire (white block, PWM) to the
terminal of the black wire (Figure 12) with a jumper, a thin wire. The heater
should be connected to the power supply, but turned off. If the fan starts to
spin – the AB is OK. 3) Check the AB for the absence of “blind spots”. For
this purpose, connect the terminal of the blue wire to the terminal of the
black wire (Figure 12) multiple times, while changing the position of the fan,
to verify if the AB starts in every position possible. If there are any “blind
spots” – the AB is defective.
21
- Check the performance of the speed measurement channel. To do this, connect
the contacts of blue and black wires (Figure 12), and measure the pulse
frequency on the green wire with a digital tester. When the AB is gaining
speed, the pulse frequency should increase. Open the contact. The AB will
start to slow down, and the pulse rate will begin to decline. If any of these
conditions is not met, the AB is faulty.
Fig.12 Control signal (PWM) connections in motor testing. In case of failure of the electric motor or the impeller (the impeller touches the volute), it is necessary to replace the whole air blower with a new one. If the fault persists with the new AB, check the CU. 5.7 Functions, Removal and Replacement of Control Unit. CU provides control of the heater, together with the controller. CU performs the following functions: ) initial assessment (check of readiness for work) of the heater components at startup; b) assessment of how the heater components function during operation; c) heater startup; d) heater shutdown:
– on command from the controller; – in case of failure of one of the controlled components; – when the controlled parameters go beyond the permissible limits
(temperature, voltage); – in case of flameout in the combustion chamber. When a malfunction of the CU is detected, make sure that connecting cables, wires and connectors of the heater have no faults. Check the controller. Replace the CU with a knowngood CU. If after replacing the CU the heater becomes operational, the old CU is considered inoperative and should be replaced.
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5.8 Functions, Removal and Replacement of Combustion Chamber.
The combustion chamber of evaporative type is designed for air-fuel mixture
combustion.
Signs of CC malfunction are: failure of the heater to start (if all other
heater elements are in good condition), reduced heat output, burnout of the
housing or internal parts of the camera, flameout.
Inoperable CC needs to be replaced. Partially dismantle the heater and
evaluate the state of the CC for deformations, soot, burning, damage of
structural elements.
When CC is replaced, is necessary to assess the condition of the heat
exchanger. If, during the assembly/disassembly any gaskets were damaged, they
should be replaced.
Components in different models:
Intermediate Unit
Combustion Chamber
Heat Exchanger
Gasket
Gasket
Fig.13 Combustion Camera in AIR-4D.
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Intermediate Unit Combustion Chamber
Heat Exchanger
Gasket
Gasket
Fig.14 Combustion Camera in AIR-4D.
Heat Exchanger
Combustion Chamber Intermediate Unit
Gasket
Gasket
Fig.15 Combustion Camera in AIR-8D.
Heaters AIR-2D had combustion cameras of two types. 1 type (till January 2015)
screen is attached directly to the CC; 2 type (after January 2015) screen
is attached through a bushing.
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Fig.16 – Bushing
Before January 2015.
After January 2015.
Fig.15 Combustion Chamber of AIR-2D heaters.
5.9 Functions, Removal and Replacement of Heat Exchanger.
The heat exchanger is designed to transfer heat from hot gases generated by
the combustion of air-fuel mixture in the CC to radiators, which in their
turn, heat up the air stream passing along the edges of radiators.
During operation of the heat exchanger such faults may occur as: loss of heat
conduction, increase in temperature of exhaust gas (more than 500°C), burn-out
of the heat exchanger walls. Failures occur due to deposits of combustion
products on the inner walls and fins of the heat exchanger and also due to the
use of a poor fuel.
Inspect the inside of the heat exchanger, clean it from soot and carbon black,
if necessary. When replacing the heat exchanger, assembly is performed in
reverse order. If, during the assembly/disassembly any gasket is damaged, it
should be replaced.
5.10 Functions, Removal and Replacement of Fuel Pump.
The fuel pump is used for metering fuel into the combustion chamber. Heaters
are equipped with fuel pumps Thomas Magnete. This pump can not be repaired, it
should be replaced with a new one.
Possible problems of the heater’s fuel pump: ) during startup, fuel is not
supplied to the fuel tube of the heater, and the characteristic knocking sound
is not heard in the fuel pump; b) the fuel pump operates, but fuel is not
supplied to the fuel tube of the heater; c) interruption of combustion when
the heater reaches its “max” mode, i.e. the fuel pump does not provide the
required amount of fuel.
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Troubleshooting and determination of productivity of the FP are performed as
follows: – before starting troubleshooting, check availability and quality of
fuel in the tank; – make sure that the wiring and connectors are in good
condition; – make sure that the FP works when the heater is turned on, and the
characteristic knocking
sound of piston movement inside the pump can be heard; It is allowed to remove
the FP and shake it to eliminate potential sticking of the piston
within the pump due to prolonged storage or failure to perform required
maintenance; To check the working condition of the FP, you can directly
connect a power supply,
corresponding to the operating voltage of the pump, to the FP terminals for a
short period (imitating pulses). If you hear the knocking sound, the fuel pump
is working; – check the tightness of the fuel line all the way from the tank
to the FP and from the FP on
to the heater.
If all of the above-mentioned problems are resolved, it is necessary to check
the fuel pump performance. The fuel pump output should be 6.57.3 ml per 100
strokes. If its performance is less or more, then the fuel pump should be
replaced.
FP performance check is carried out by means of the fuel-priming device UPT-4.
5.11 Functions, Removal and Replacement of Controller.
The controller (Fig.17(a)) has the following functions: – start and stop of
the heater in manual mode; – choice of operation modes, by power or by
temperature; – display of the set temperature or power; – display of
temperature (from the sensor integrated in the heater, the controller, or
remote when connected); – Display of a fault code in case of heater
malfunction.
The controller (Fig.17(b)) has the following functions: – Starting the heater
for an unlimited time. – Adjustment of the heat output of the heater. –
Adjusting the temperature of the heated air (when connecting the cabin
sensor). – Indication of the status of the heater by LED.
To determine the performance of the controller, press any button on the
controller. It causes a light indicator on the controller to illuminate.
Fig. 17 () Controller PU22
Fig.17 (b) – Controller PU5
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If when you press a button, the indicator on the controller does not light up,
check the wiring, the power supply voltage of the controller, and electrical
contacts of the terminals.
Any dirt or oil should be wiped off the contacts with a clean cloth soaked in
gasoline. If after the removal of defects the controller still does not work,
it is necessary to replace the controller. If after the replacement the cause
of the fault is corrected, the old controller is considered to be inoperable
and it should be replaced. The controller can not be repaired, it should be
replaced by a new one. If after the replacement of the controller the heater
malfunction persists, check the wiring and the CU.
5.12 Functions, Troubleshooting and Replacement of Cabin Sensor (it is available as an option)
The cabin sensor (Figure 18) is used to measure air temperature in the area of
its installation, and it allows to maintain desired temperatures within 1
30°C.
The performance of installed sensor can be determined by the operation of the
heater. If the heater does not maintain the desired temperature: – measure the
temperature in the sensor area and compare its value with the value
displayed on the CNTRL; – replace the sensor with a known good and retest. If
the heater with a new sensor is working properly, the old sensor is defective
and should be replaced. If the heater with a new sensor still does not
maintain the set temperature – check the CU.
RED
2
1
12±1
BLACK
5020 + 2 0
(1 chip; 2 – pin connector) Fig. 18 Cabin Sensor
Sensor performance (during heater operation) can be determined by the output
voltage. The output voltage at 0°C – 2.73V. The voltage increases with
increasing temperature. As the temperature increases by 1°C, the output
voltage will increase by 10mV.
Attention! The cabin sensor, if installed, should be disabled, if you have to
run the heater when the air temperature is more than 30.
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6 Tools and Equipment for Maintenance and Repairs.
6.1 Test Stand. Maintenance and repair of liquid and air heaters is carried
out on the stationary test stand
DV 1105.000 (Figure 19). The stand is designed for the following operations:
a) testing liquid and air heaters using a diagnostic device and determination
of their faults;
b) checking the performance of a fuel pump, air blower, temperature and
overheat sensors, flame indicator, glow plug;
c) checking the performance of liquid and air heaters after repairs. Key
features and work procedures on the stand are described in the operation
manual
for DV 1105.000.
Fig 19- Test Stand.
Note. This stand allows you to perform quick and high quality repairs of
liquid and air heaters.
6.2 USB adapter.
The USB adapter is designed for connecting liquid and air heaters to a personal
computer (PC). It is used to obtain data on the status of the liquid or air heater.
The program starts Air heaters from computer and reads data from the heaters:
– start number,
– supply voltage in V,
– current mode of operation,
– flame indicator value in standard units,
– software version,
– fuel pump frequency in Hz,
– air inlet temperature in °C,
– electric motor speed.
For more information, refer to the instruction manual of the USB adapter.
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7 Heater Check after Repair. 7.1 After repair, the heater should be tested for
efficiency on the DV1105.000 stand, and
after that it can be installed on the vehicle. (The heater can also be tested
on the vehicle on which it will be used).
7.2 Connect the heater to a 12 or 24 V power supply (depending on the heater)
and to the fuel tank. Then fill the fuel line to the heater by means of a fuel
priming device. Start the heater. The heater should start at the minimum power
mode which is set by the controller. The heater should operate at the minimum
power mode for at least 10 minutes. While changing the power mode of the
heater by means of the controller from the minimum to the maximum value, make
sure that the intensity of heating increases.
7.3 At maximum power mode, measure the temperature difference between the
inlet and the outlet of the heater, the exhaust gas temperature, and carbon
monoxide (CO) content. Temperature difference between inlet and outlet should
be at least 7090. Exhaust gas temperature should be not more than 500. The
carbon monoxide (CO) content should be not more than 0.1%. After conducting
the measurements, switch off the heater. The LED on the controller will blink
frequently, which means that the purging process is underway in the combustion
chamber. After purging is finished, the LED will blink infrequently, which
means that the heater is not working. When the work is completed, turn off the
power and dismount the heater from the test stand.
If in the process of starting or running the heater, there was a crash, for
whatever reason, and the heater was turned off, the display panel of the
controller will show a fault code. Once the cause of the failure is corrected,
the test should be repeated.
When the heater is mounted on the vehicle after the repair, it should be
checked for proper operation both with with engine off and on.
Attention! The cabin sensor, if installed, should be disabled, if you have to
run the heater when the air temperature is more than 30.
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