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Coolant Heater
Thermo 90
Thermo 90 S
Workshop Manual
Webasto Thermosystems Inc.
North America
3333 John Conley Drive
Lapeer, MI 48446
Phone (810) 245-2400
Toll-free (800) HEATER-1
Fax (810) 664-7720
Technical Assistance Hotline
USA: (800) 555-4518
Canada: (800) 667-8900
Rev. 03/2000 907400 www.webasto.com
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THERMO 90 / 90 S TABLE OF CONTENTS Table of Contents 1. Introduction 1.1 Scope and Purpose . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1-1 1.2 Meaning of Warnings, Cautions and Notes . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1-1 1.3 Additional Documentation to be used . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1-1 1.4 General Safety Regulations and Information . . . . . . . .
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TABLE OF CONTENTS THERMO 90 / 90 S 5.4.1 Reading and Removing Error Codes Stored in Memory using the PC Diagnostics Kit P.N. 92542C . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5-3 5.5 Visual Inspection for Assessment of Burner Condition . . . . . . . . . . . . . . . . . . . . . . . . . . 5-4 5.5.1 Burner Housing . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5-4 5.5.2 Rear Wall with Metal Evaporator . . . . . . . . . . .
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THERMO 90 / 90 S TABLE OF CONTENTS 8.7.1.2 Installation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8-7 8.7.2 Replacement of Circulation Pump . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8-7 8.7.3 Replacement of Temperature Limiter . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8-7 8.7.4 Replacement of Temperature Sensor . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8-7 8.7.5 Rep
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THERMO 90 / 90 S 1INTRODUCTION 1.4 General Safety Regulations and 1. Introduction Information 1.1 Scope and Purpose The general safety regulations for the prevention of accidents and relevant operating safety instructions must This repair shop manual is intended to support be observed at all times. familiarized personnel in the repair of Thermo 90 and Thermo 90 S coolant heaters. The specific safety regulations applicable to this manual are highlighted in the individual chapters by Warnings, The
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1INTRODUCTION THERMO 90 / 90 S Ignoring the installation instructions and its procedures This does not apply for towing vehicles with an open will void the warranty granted by Webasto. The same cockpit. applies for repairs preformed by unskilled, unauthorized personnel and repairs without using genuine Webasto All fuel containers offered in the Webasto spare parts. This will void the coolant heaters “Official Accessories Catalog are suitable for a maximum Marks of Conformity.” operating pressu
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THERMO 90 / 90 S 2GENERAL DESCRIPTION diesel operated coolant heaters for up to 2 hours after 2. General Description heater actuation. The Webasto Thermo 90 and 90 S coolant heater, in The Webasto Thermo 90 and 90 S coolant heaters combination with the vehicle’s own heating system, is basically consist of: used to: • combustion air fan • heat the cab, sleeper or interior areas of vehicles • heat exchanger • defog/defrost windshields • burner insert with combustion tube • preheat water cooled eng
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2GENERAL DESCRIPTION THERMO 90 / 90 S 1 Combustion Air Fan 2 Fuel Connection 3 Temperature Sensor 4 Temperature Limiter 5 Heat Exchanger 6 Inlet, Coolant 7 Circulation Pump 8 Outlet, Coolant 9 Outlet, Exhaust 10 Inlet, Combustion Air 11 Control unit (may also be located Heater Thermo 90 S remotely in the vehicle) 2.1 Combustion Air Fan 2.2 Heat Exchanger The combustion air fan delivers the air required for The heat exchanger transfers the heat provided by combustion from the combustion air inlet
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THERMO 90 / 90 S 2GENERAL DESCRIPTION 2.3 Temperature Sensor 2.8 Combustion Tube The temperature sensor senses the coolant temperature Inside the combustion tube the combustion of the fuel/air in the heat exchanger of the heater unit as electrical mixture takes place, heating up the heat exchanger. resistance. This signal is fed to the control unit for processing. 2.4 Temperature Limiter The overheat protection (bimetal) protects the heater unit from excessive operating temperatures. The overh
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THERMO 90 / 90 S 3FUNCTIONAL DESCRIPTION 3.4 Switch-off 3. Functional Description (Fig. 3-1) When switching the heater off, the operation indicator on the timer/switch extinguishes. Combustion ends and the run-down cycle is initiated. The circulation pump and 3.1 Switch-on combustion air fan, however, continue operation to cool down the heater (run-down) and are automatically When operating the push button "Immediate Heating", deactivated after about 90 seconds. A reactivation of the the "Ope
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3FUNCTIONAL DESCRIPTION THERMO 90 / 90 S Fig. 3-1 Functional Sequence Functional Sequence for Thermo 90/90 S Setting of Control Temperatures - Thermo 90 1 Switch-on Table Rated Temp. Control Reactivation 2 Configuration Check at Sensor Idle after 3 Preheating 40 sec. (cycled) Control Idle 4 Fuel Dosing Pump Priming 5 - 7 sec. (1) 5 Fuel Dosing Pump / Part Load (1/4) Minus to B6 80 °C 90 °C 75 °C 6 Flame Sensor Take-over B6 not used 72 °C 82 °C 67 °C 7 Stabilization Period Plus to B6 65 °C 75 °C
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THERMO 90 / 90 S 3FUNCTIONAL DESCRIPTION 3.5 Malfunctions 3.5.3 Diagnosis after Switch-off upon Failure (Thermo 90 S) 3.5.1 Switch-off upon Failure When equipped with a standard timer model 1531, an error code will be indicated on the timer display: In case of a no-flame condition, fuel is delivered for a maximum of 180 seconds. F 01 No start (after 2 start attempts) F 02 Flame-out during operation (repeated > 5) In the event of a flame-out during operation, fuel is F 03 Voltage too low or too h
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THERMO 90 / 90 S 4TECHNICAL DATA Electrical Components: 4. Technical Data (Standard Measure) Control unit, combustion air fan motor and fuel dosing As long as no threshold values are given, the following pump, glow pin, control switch and timer are either of the technical data is understood to include tolerances of 12V or 24V type. ±10% usual for heaters at an ambient temperature of The components temperature limiter, temperature sensor +68 °F and at nominal voltage and conditions. and flame sen
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4TECHNICAL DATA THERMO 90 / 90 S Electrical Components: 4. Technical Data (Metric Measure) Control unit, combustion air fan motor and fuel dosing As long as no threshold values are given, the following pump, glow pin, control switch and timer are either of the technical data is understood to include tolerances of 12V or 24V type. ±10% usual for heaters at an ambient temperature of The components temperature limiter, temperature sensor +20 °C and at nominal voltage and conditions. and flame senso
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THERMO 90 / 90 S 5TROUBLESHOOTING 5. Troubleshooting CAUTION Troubleshooting is normally limited to the isolation of defective components. 5.1 General The following defects are not included in the troubleshooting procedures. Before troubleshooting, This section describes troubleshooting procedures for check for and eliminate these defects: the Thermo 90 and Thermo 90 S coolant heaters. - fuel supply (plugged fuel filter or no fuel) CAUTION - corrosion on battery terminals Troubleshooting requir
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5TROUBLESHOOTING THERMO 90 / 90 S The heater Thermo 90 S, with standard timer, outputs 5.3 Failure Symptoms after Switch-off errors to the timer display for indication (see 3.6.3). upon Failure The following table may also be used as representative reference. NOTE: When operated with a switch the type of failure is indicated by a flash code of the operation indicator light during heater run-down. After five short signals the long flash pulses are counted. Failure Symptom Probable Cause Remedy No
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THERMO 90 / 90 S 5TROUBLESHOOTING Failure Symptom Probable Cause Remedy 8 Flash pulses (F 08) Wiring Check wiring for damage, open (combustion air fan) connections or short circuit Combustion air fan defective Replace replace combustion air fan 9 Flash pulses (F 09) Wiring Check wiring for damage, open (glow pin) connections or short circuit Glow pin defective Replace glow pin 10 Flash pulses (F 10) Coolant circuit Check coolant level (temperature limiter Bleed coolant circuit Thermo 90 S only)
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5TROUBLESHOOTING THERMO 90 / 90 S 5.5 Visual Inspection for Assessment 5.5.1 Burner Housing of Burner Condition • The starting air bore (Fig. 5-3) must not be clogged, Burner and evaporator have specific features indicating otherwise there will be no start. their need for replacement or their serviceable condition. The following describes the criteria for a correct Remedy inspection. Carefully remove any contamination with a wire of 1.5 mm diameter. Remove glow pin first. 1 Fuel Inlet Pipe 2 O
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THERMO 90 / 90 S 5TROUBLESHOOTING 5.5.2 Rear Wall with Metal Evaporator 5.5.3 Combustion Chamber • The pilot flame exit bore (Fig. 5-4) must not be • The combustion chamber (Fig. 5-5) should not be clogged, otherwise there will be no start. damaged (e.g. dented). A combustion chamber with dents may cause Remedy insufficient combustion or coking of the heater. Replace burner assembly Remedy Replace burner assembly • Cracks, delaminations, as well as black or other discolorations of the evaporator
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THERMO 90 / 90 S 6FUNCTIONAL TESTS 6.3.3 Flame Sensor Resistance Test 6. Functional Tests During electrical testing of the flame sensor using a 6.1 General digital multi-meter, the following readings should be obtained: This section describes the on-vehicle and off-vehicle testing of the heater to check for proper operation. Cold Test: Resistance at 25 °C (77 °F): 2.6 … 3.4 Ω Test current: < 5 mA WARNING The heater must not be operated, not even with timer, in Hot test: enclosed areas like garag
