Webasto Scholastic Heater Service And Repair Manual

Webasto Scholastic Heater Service And Repair Manual

Used in combination with the vehicle’s own heating installation to heat the passenger compartment, defrost the windshield, preheat water-cooled engines, in self-contained cargo heating applications
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– 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.
Service and Repair
Manual
Coolant Heaters
DBW 2010
DBW 2020
DBW 300
Circulation Pumps
U4810
U4814
U4846
U4851

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Summarization of Contents

1. INTRODUCTION
1.3 MEANING OF WARNINGS, CAUTIONS AND NOTES
Explains the significance of different warning styles (Danger, Warning, Caution, Note) used in the manual.
1.5 SAFETY INFORMATION AND REGULATIONS
Outlines general safety rules and specific regulations applicable to Webasto heaters.
1.5.1 GENERAL SAFETY NOTES
Provides essential safety guidelines for heater operation, installation, and environment.
1.6 LEGAL PROVISIONS FOR INSTALLATION
Details regulatory compliance and requirements for installing Webasto heaters in vehicles.
2.1 PARTS OF THE HEATER
2.1.1 ELECTRONIC CONTROL UNIT
Details the function of the SG 1553 control unit for heater operation and monitoring.
2.1.2 OVERHEAT FUSE
Explains the overheat fuse's role in protecting the heater from excessive temperatures.
2.1.3 TEMPERATURE LIMITER
Describes the temperature limiter's function and automatic reset behavior.
2.1.4 TEMPERATURE CONTROL THERMOSTAT
Explains how the thermostat regulates coolant temperature by cycling the heater.
2.1 PARTS OF THE HEATER
2.1.5 FLAME DETECTOR
Details the photosensitive flame detector that signals flame status to the control unit.
2.1.6 COMBUSTION AIR INTAKE
Explains the air intake's function in regulating combustion air quantity.
2.1 PARTS OF THE HEATER
2.1.7 COMBUSTION AIR FAN (5) AND MOTOR (2)
Describes the fan and motor assembly responsible for supplying combustion air and driving the fuel pump.
2.1 PARTS OF THE HEATER
2.1.8 COUPLING
Explains the mechanical connection between the motor and the combustion air fan.
2.1.9 TOOTHED GEARING
Details the gears that drive the fuel pump with a specific ratio.
2.1.10 FUEL PUMP
Describes the fuel pump's function, pressure delivery, and types for different models.
2.1.11 FUEL CONTROL VALVE AND SOLENOID
Explains the solenoid valve's role in interrupting fuel supply.
2.1 PARTS OF THE HEATER
2.1.12 FUEL NOZZLE AND NOZZLE HOLDER
Details the fuel nozzle's function in atomizing fuel for combustion.
2.1.13 FUEL LINE CONNECTIONS
Describes fuel line configurations for different heater models.
2.1.14 ELECTRONIC IGNITION UNIT
Explains the ignition unit's function in producing a spark for starting.
2.1.15 IGNITION ELECTRODES
Describes the electrodes that form the spark for combustion.
2.1 PARTS OF THE HEATER
2.1.16 COMBUSTION CHAMBER AND AIR SWIRLER
Explains where the air-fuel mixture is burned within the combustion chamber.
2.1.17 HEAT EXCHANGER
Describes how heat is transferred to the coolant.
2.1.18 PREHEAT THERMOSTAT
Explains the thermostat's function in warming the fuel for atomization.
2.1.19 PRE-HEATER CARTRIDGE
Details the heating element in the nozzle holder for cold weather.
2.1 PARTS OF THE HEATER
2.1.20 COOLANT CIRCULATING PUMP
Describes the externally mounted pump that ensures coolant circulation.
3. FUNCTIONAL DESCRIPTION
3.1 SWITCH ON
Explains the sequence of operations when the heater is turned on.
3.2 HEATING OPERATION
Describes how the heater maintains coolant temperature during operation.
3.3 SWITCH OFF
Details the shutdown procedure and run-down sequence.
4. TECHNICAL DATA
4.1 TECHNICAL DATA OF THE HEATERS
Provides specifications for DBW heaters, including output, fuel consumption, and dimensions.
4.2 TECHNICAL DATA OF THE CIRCULATING PUMPS
Lists technical specifications for various coolant circulating pumps.
4.3 PERMISSIBLE EXTENSION OF THE CONNECTIONS
Specifies maximum lengths and dimensions for fuel, air intake, and exhaust lines.
5. TROUBLESHOOTING
5.1 QUICK CHECK TROUBLESHOOTING MATRIX
A matrix to quickly diagnose problems by checking components.
5.2 TESTER INSTRUCTIONS
Instructions for using a specific tester to diagnose heater components.
5.2.1 TEST PROCEDURES
Outlines the steps for setting up and performing component tests with the tester.
5. TROUBLESHOOTING
5.3 INSTRUCTIONS FOR FAULT FINDING
Provides guidance for diagnosing specific heater faults using flowcharts.
5.3.1 COMBUSTION STARTS IMMEDIATELY WHEN HEATER IS SWITCHED ON
Troubleshooting steps for immediate combustion upon heater activation.
5.3.2 HEATER DOES NOT START WHEN SWITCHED ON
Diagnostic flow for when the heater fails to start.
5. TROUBLESHOOTING
5.3.3 AFTER SWITCHING ON, THE HEATER SWITCHES OFF AFTER APPROX. 30 SECONDS ON FAULT
Troubleshooting for heaters shutting off shortly after starting due to a fault.
5. TROUBLESHOOTING
5.3.4 HEATER STARTS ONLY AFTER SEVERAL STARTING ATTEMPTS
Diagnostic steps for heaters requiring multiple attempts to start.
5.3.5 HEATER SWITCHES OFF BY ITSELF DURING OPERATION
Troubleshooting for heaters shutting off unexpectedly during normal operation.
5. TROUBLESHOOTING
5.3.6 HEATER SMOKES
Diagnostic guide for identifying and resolving smoke issues during heater operation.
5. TROUBLESHOOTING
5.3.7 HEATER SMOKES
Continuation of troubleshooting for heater smoke issues.
5.3.8 HEATER CANNOT BE SWITCHED OFF
Troubleshooting steps for when the heater fails to turn off.
6. FUNCTIONAL ADJUSTMENTS
6.1 GENERAL
Introduces tests and adjustments to ensure heater serviceability.
6.2.1 ADJUSTMENT OF CO2 CONTENTS
Procedure for adjusting combustion air to set CO2 levels in exhaust gas.
6. FUNCTIONAL ADJUSTMENTS
6.2.2 FLAME DETECTOR RESISTANCE CHECK
Method for checking the flame detector's resistance under different light conditions.
6.2.3 IGNITION ELECTRODE CHECK AND SETTING
Guide for checking and setting the gap of ignition electrodes for proper sparking.
6. FUNCTIONAL ADJUSTMENTS
6.2.4 IGNITION COIL CHECK
Procedures for checking the ignition coil's output and spark.
6.2.5 FUEL PUMP CHECK
Steps for checking fuel pump pressure and adjusting it as needed.
6. FUNCTIONAL ADJUSTMENTS
6.2.6 FUEL SOLENOID VALVE CHECK
How to check the fuel solenoid valve for proper clicking and function.
6.2.7 NOZZLE BLOCK PRE-HEATER CHECK
Procedure for checking the pre-heater cartridge's resistance.
7. CIRCUIT DIAGRAMS
7.1 DBW 2010 12 V AND 24 V - Early CANADIAN VERSION
Wiring diagram for the DBW 2010 in early Canadian configurations.
7. CIRCUIT DIAGRAMS
7.2 DBW 2010 12 V AND 24 V - PRESENT NORTH AMERICAN VERSION
Wiring diagram for the DBW 2010 in present North American configurations.
7. CIRCUIT DIAGRAMS
7.3 DBW 2020 / 300 12 V AND 24 V - WITHOUT NOZZLE PREHEAT
Wiring diagram for DBW 2020/300 without nozzle preheat.
7. CIRCUIT DIAGRAMS
7.4 DBW 2020 / 300 12 V AND 24 V - WITH NOZZLE PREHEAT
Wiring diagram for DBW 2020/300 with nozzle preheat.
7. CIRCUIT DIAGRAMS
7.5 SCHOLASTIC HEATER 12 V - WITH ON/OFF SWITCH
Wiring diagram for the Scholastic Heater with an ON/OFF switch.
7. CIRCUIT DIAGRAMS
7.6 SCHOLASTIC HEATER 12 V - WITH 7-DAY TIMER MODEL 1529
Wiring diagram for Scholastic Heater with a 7-day timer model 1529.
7. CIRCUIT DIAGRAMS
7.7 SCHOLASTIC HEATER 12 V - WITH 7-DAY TIMER MODEL 1531
Wiring diagram for Scholastic Heater with a 7-day timer model 1531.
7. CIRCUIT DIAGRAMS
7.8 CONTROL UNIT - IDENTIFICATION OF TERMINALS
Details the terminal identification for the heater's control unit.
8. SERVICING
8.2 HEATER SERVICING
Provides recommendations and procedures for maintaining the heater.
8.4 HEATER TEST RUN
Guidelines for performing a test run of the heater.
8.5 MAINTENANCE
Lists essential maintenance tasks for heater reliability.
8.5.1 BURNER HEAD OPENING AND CLOSING
Step-by-step guide for opening and closing the burner head.
8. SERVICING
8.6 VISUAL INSPECTIONS AND REGULATIONS FOR INSTALLATION
Covers visual checks and installation regulations.
8.6.1 CONNECTION TO VEHICLE COOLING SYSTEM
Details how to connect the heater to the vehicle's cooling system.
8.6.2 CONNECTION TO VEHICLE FUEL SYSTEM
Explains connecting the heater to the vehicle's fuel supply.
8.6.3 COMBUSTION AIR SUPPLY
Regulations and placement advice for the combustion air intake.
8. SERVICING
8.6.4 EXHAUST LINE
Regulations and guidelines for installing the exhaust line.
8. SERVICING
8.7 REMOVAL AND INSTALLATION
Step-by-step instructions for removing and installing the heater.
8.7.1 HEATER, REMOVAL AND INSTALLATION
Step-by-step instructions for removing and installing the heater.
8.7.2 TEMPERATURE LIMITER, REPLACEMENT
Steps to replace the temperature limiter.
8.7.3 TEMPERATURE THERMOSTAT, REPLACEMENT
Steps to replace the temperature control thermostat.
8. SERVICING
8.7.4 OVERHEAT FUSE, REPLACEMENT
Steps to replace the overheat fuse.
8.7.5 BURNER HEAD, REPLACEMENT
Steps to replace the burner head.
8. SERVICING
8.8.2 FUEL SUPPLY SYSTEM, BLEEDING
Procedure for bleeding the fuel supply system.
9. REPAIR
9.1 GENERAL INFORMATION
General information and warnings before performing repairs.
9.1.1.1 VISUAL INSPECTION, GENERAL
General visual checks for components, wiring, and contacts.
9.1.1.2 COMBUSTION CHAMBER, VISUAL INSPECTION
Visual inspection of the combustion chamber for deposits or damage.
9.1.1.3 HEAT EXCHANGER, VISUAL INSPECTION
Visual inspection of the heat exchanger for deposits and damage.
9. REPAIR
9.2 DISASSEMBLY AND ASSEMBLY
Procedures for disassembling and assembling heater components.
9.2.1 OVERHEAT FUSE, REPLACEMENT
Steps to remove and install the overheat fuse.
9.2.2 TEMPERATURE CONTROL THERMOSTAT, REPLACEMENT
Steps to remove and install the temperature control thermostat.
9. REPAIR
9.2.3 TEMPERATURE LIMITER, REPLACEMENT
Steps to remove and install the temperature limiter.
9.2.4 CONTROL UNIT, REPLACEMENT
Steps to remove and install the control unit.
9.2.5 BURNER, REPLACEMENT
Steps to remove and install the burner assembly.
9. REPAIR
9.2.6 FUEL VALVE AND SOLENOID, REPLACEMENT
Steps to replace the fuel valve and solenoid assembly.
9.2.7 FUEL PUMP, REPLACEMENT
Steps to remove and install the fuel pump.
9. REPAIR
9.2.8 FUEL NOZZLE, REPLACEMENT
Steps to remove and install the fuel nozzle.
9.2.9 FLAME DETECTOR, REPLACEMENT
Steps to remove and install the flame detector.
9. REPAIR
9.2.10 IGNITION ELECTRODES, REPLACEMENT
Steps to remove and install the ignition electrodes.
9.2.11 IGNITION COIL, REPLACEMENT
Steps to remove and install the ignition coil.
9. REPAIR
9.2.12 DRIVE MOTOR, REPLACEMENT
Steps to remove and install the drive motor.
9. REPAIR
9.2.13 COMBUSTION AIR FAN, REPLACEMENT
Steps to remove and install the combustion air fan.
9.2.14 FAN REPLACEMENT
Steps for replacing the fan.
9. REPAIR
9.2.15 FAN SHAFT, BEARINGS AND GEARING, EXPLODED VIEW (DBW 2010)
Exploded view of the fan shaft, bearings, and gearing for DBW 2010.
9. REPAIR
9.2.16 FAN SHAFT, BEARINGS AND GEARING, EXPLODED VIEW (DBW 2020 / DBW 300)
Exploded view of fan shaft, bearings, and gearing for DBW 2020/300.
9. REPAIR
9.2.17 COMBUSTION CHAMBER, REPLACEMENT
Steps to remove and install the combustion chamber.
9.2.18 HEAT EXCHANGER, REPLACEMENT
Steps to remove and install the heat exchanger.
9.3 COOLANT CIRCULATING PUMP REPAIR
9.3.1 REMOVAL
Steps to remove the coolant circulating pump.
9.3.2 DISASSEMBLING
Steps to disassemble the coolant circulating pump.
9.3.3 ASSEMBLING
Steps to assemble the coolant circulating pump.
9.3.4 INSTALLING
Steps to install the coolant circulating pump.
9.4 MP SCHOOL BUS CIRCULATION PUMP
9.4.1 REMOVAL
Steps to remove the MP School Bus circulation pump.
9.4.2 DISASSEMBLING
Steps to disassemble the MP School Bus circulation pump.
9.4.3 ASSEMBLING
Steps to assemble the MP School Bus circulation pump.
9.4.4 INSTALLING
Steps to install the MP School Bus circulation pump.
10. INSTRUMENTS AND TOOLS
10.1 SETTING GAUGE
Tool used for setting electrode gap and fuel nozzle distance.
10.2 TESTER
Tool for testing heater components and general troubleshooting.
10.3 CO2 TEST APPARATUS
Apparatus for measuring CO2 content in exhaust gases.
10.4 SMOKE NUMBER TEST APPARATUS
Apparatus used for checking smoke number.
10. INSTRUMENTS AND TOOLS
10.5 NOZZLE WRENCH
Tool for replacing high-pressure fuel nozzles.
10.6 FUEL PRESSURE GAUGE
Gauge for checking and adjusting fuel pressure.
10.7 GREASE AND LOCKING VARNISH
Lubricants and sealants for maintenance and adjustments.
11. PRODUCT INFORMATION
11.1 ISS "WHITE" TIMER FOR THE SCHOLASTIC HEATER™
Installation and operation instructions for the ISS "White" timer.
11. PRODUCT INFORMATION
Setting the Timer
Instructions on how to set the clock and timer functions for the ISS "White" timer.
11. PRODUCT INFORMATION
Operation in manual mode
How to operate the timer manually and safety precautions.

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