Webasto Thermo 90 ST D Service And Repair Manual
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Webasto Thermo 90 ST D Service And Repair Manual

Webasto Thermo 90 ST D Service And Repair Manual

Coolant heater
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See also: Workshop Manual , Instruction and Installation Manual
Coolant Heater
Thermo 90 ST D (Diesel)
Thermo 90 ST 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.

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Summary of Contents for Webasto Thermo 90 ST D

  • Page 1 – 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.

  • Page 3: Table Of Contents

    7.2 Thermo 90 ST Circuit Diagram Legend ............21 www.webasto.us Webasto Product N.A., Inc.
  • Page 4 Replacing the Heat Exchanger ............41 Webasto Product N.A., Inc.
  • Page 5 9.2.7.2 Installation ..............41 10.Product Information www.webasto.us Webasto Product N.A., Inc.
  • Page 6 TABLE OF CONTENTS THERMO 90 ST Webasto Product N.A., Inc. www.techwebasto.com...

  • Page 7: Introduction

    Webasto. The same applies if repairs are Any special safety regulations relevant to this instruction carried out incorrectly or with the use of parts other than manual will be highlighted in the relevant sections or text genuine spare parts.

  • Page 8: Suggestions For Improvements And Changes

    1.5 S UGGESTIONS FOR MPROVEMENTS AND HANGES Complaints, improvement suggestions or corrections relating to this workshop manual should be addressed Webasto Product North America, Inc. Technical Documentation Group 15083 North Road Fenton MI 48430 Phone: 810.593.6000 PC-Fax: 810.593.6135 Webasto Product N.A., Inc.

  • Page 9: General Description

    2 hours after the heater is switched on. Combustion air fan Fuel connection Temperature sensor Temperature limiter Heat exchanger Inlet, coolant Circulating pump Outlet, coolant Outlet, exhaust gas 10 Inlet, combustion air 11 Control unit Figure 1: Thermo 90 ST heater www.webasto.us Webasto Product N.A., Inc.

  • Page 10: Combustion Air Fan

    The signals are fed to the control unit where Figure 3: Heat exchanger they are processed. The flame status is monitored by the flame monitor whenever the heater is operating. Webasto Product N.A., Inc. www.techwebasto.com...

  • Page 11: Combustion Pipe

    The solenoid coil of the metering pump receives its pulses from the microprocessor in the control unit. 0-90° 0-90° 0° Figure 8: Fuel metering pump Figure 6: Circulating pump www.webasto.us Webasto Product N.A., Inc.
  • Page 12 GENERAL DESCRIPTION THERMO 90 ST This page for your notes. Webasto Product N.A., Inc. www.techwebasto.com...

  • Page 13: Functional Description

    The temperature in the cabin can also be controlled using The heater restarts when the coolant cools to the preset the vehicle’s own heater fan with a cabin thermostat. temperature for switching back on. www.webasto.us Webasto Product N.A., Inc.
  • Page 14 Flame monitor take-over Stabilization time Stabilization time Coolant temperature reduced Full load Full load Vehicle fan “On” Switch off (run-on) Control range Flame monitor “Cold” (0) Control pause Run-on ended (cool-down) Flame monitor “Cold” (0) Webasto Product N.A., Inc. www.techwebasto.com...

  • Page 15: Malfunctions

    Temperature sensor interrupt or temperature sensor short circuit Metering pump interrupt or metering pump short circuit Fan motor interrupt or fan motor short circuit or fan motor incorrect speed Glow pin interrupt or glow pin short circuit Overheating www.webasto.us Webasto Product N.A., Inc.
  • Page 16 FUNCTIONAL DESCRIPTION THERMO 90 ST This page for your notes. Webasto Product N.A., Inc. www.techwebasto.com...

  • Page 17: Technical Data

    12 V and 24 V heaters. system is filled with the new fuel. The Thermo 90 ST D heater is also licensed for use with PME (bio-diesel), which complies with ASTM D6751 and DIN EN 14214.
  • Page 18 TECHNICAL DATA THERMO 90 ST HEATER Operation THERMO 90 ST B THERMO 90 ST D In Exhaust Gas Maximum 10... 12.0% by volume (permitted function range) adjustment values at approx. +20 °C Maximum 0 m (0 ft) 500 m (1640 ft) 1000 m (3280 ft) 10.6%...

  • Page 19: Troubleshooting

    Control unit enters fault lock-out status. automatically Switch heater off and then on again. Flame extinguishes during operation Contact a Webasto service facility if heater operation does not start again. Heater overheats due to lack or loss of Top up coolant.

  • Page 20: Fault Indications On Fault Lock-Out

    Check cabling for damage, discontinuity and (flame monitor defective) short-circuit Flame monitor defective Replace flame monitor Flashing pulses Cabling Check cabling for damage, discontinuity and (temperature sensor short-circuit defective) Temperature sensor defective Replace temperature sensor Page 1 of 2 Webasto Product N.A., Inc. www.techwebasto.com...

  • Page 21: Fault Indications On Fault Lock-Out

    F 09 Ceramic glow pin possible. Switch heater on. F 10 Overheat condition F 11 Coolant circulating pump Contact a Webasto service facility if heater operation cannot be restored. F 02 Flame failure After 6 consecutive attempts, heater and control unit are locked out.

  • Page 22: Visual Check For Assessing The Burner

    1.5 mm or 1/16 in. diameter wire). Remove the glow pin first. 1 Fuel pipe 2 Round seal 3 Flame monitor 4 Insulation 5 Glow pin 6 Housing 7 Screw 8 Bar 9 Start air hole Figure 10: Visual check, burner back wall Webasto Product N.A., Inc. www.techwebasto.com...
  • Page 23 The insulation (item 4, Fig. 10) must not be missing. Pilot flame outlet opening Air swirl plate Combustion chamber Air holes Metal evaporator, diesel Gap between housing and combustion chamber Figure 11: Visual check, pilot flame outlet opening Figure 12: Visual check, complete burner www.webasto.us Webasto Product N.A., Inc.
  • Page 24 TROUBLESHOOTING THERMO 90 ST This page for your notes. Webasto Product N.A., Inc. www.techwebasto.com...

  • Page 25: Functional Tests

    Test current: < 1 mA Speed in control range min. 1800 rpm (±9%) Speed in control range max. 5600 rpm (±9%) Install a new combustion air fan if the speeds are outside tolerance (see 9.2.4). www.webasto.us Webasto Product N.A., Inc.
  • Page 26 FUNCTIONAL TESTS THERMO 90 ST This page for your notes. Webasto Product N.A., Inc. www.techwebasto.com...

  • Page 27: Circuit Diagrams

    Vehicle fan interface Fuse 5 A ATM mini flat fuse harness option Fuse 20 A ATM mini flat fuse Metering pump Fuel pump for heater “Heating” symbol in Operating indicator the display (in item P2) www.webasto.us Webasto Product N.A., Inc.
  • Page 28 CIRCUIT DIAGRAMS THERMO 90 ST Figure 13: Thermo 90 ST with On/Off switch - connection diagram (Includes optional blower interface harness) Webasto Product N.A., Inc. www.techwebasto.com...
  • Page 29 THERMO 90 ST CIRCUIT DIAGRAMS Figure 14: Thermo 90 ST with 7-day digital timer model 1531 - connection diagram www.webasto.us Webasto Product N.A., Inc.
  • Page 30 CIRCUIT DIAGRAMS THERMO 90 ST This page for your notes. Webasto Product N.A., Inc. www.techwebasto.com...

  • Page 31: Servicing Work

    Replace the fuel filter if there is one. CAUTION: A temperature of 90 °C (194 °F) must not be exceeded in the vicinity of the heater in any circumstances (for example when completing painting work on the vehicle). See Section 4. www.webasto.us Webasto Product N.A., Inc.
  • Page 32 SERVICING WORK THERMO 90 ST Figure 15: Installation example of a heater in a truck Webasto Product N.A., Inc. www.techwebasto.com...

  • Page 33: Visual Inspections And Installation Instructions

    NOTE: A sign must be affixed to the fuel filler 6 liters (6.34 quarts) of coolant. neck warning that the heater must be switched The coolant hoses supplied by Webasto must always be off before refuelling. used. If you do not use these hoses, the hoses that you do use must comply with DIN 73411.

  • Page 34: Fuel Extraction

    Sealing ring Fuel may only be taken from the supply or return line using the special Webasto fuel extractor tee (Fig. 20). The fuel extractor must be fitted in such a way that any air or gas bubbles are automatically discharged towards the tank (Fig.

  • Page 35: Fuel Lines

    The metering pump is a combined delivery, metering and To Fuel Metering Pump shut-off system and is subject to certain installation criteria (Fig. 16 and 22). Figure 20: Webasto fuel extractor tee installation 8.6.2.2 F INES 12 V and 24 V – Diesel DP 30 (with damper)

  • Page 36: Installation And Attachment

    The size of the ventilation opening must be increased As a result of the risk of corrosion, only genuine Webasto accordingly if the temperature in the box exceeds the parts may be used for the plug connections between the permitted ambient temperature of the heater (see metering pump and the metering pump wiring harness.

  • Page 37: Removal And Installation

    3 screws with washers to attach it. secure. If the heater suffers a fault during operation, the fault must be located and remedied (see section 5). www.webasto.us Webasto Product N.A., Inc.
  • Page 38 SERVICING WORK THERMO 90 ST This page for your notes. Webasto Product N.A., Inc. www.techwebasto.com...

  • Page 39: Repair

    (4). deformation, wear, etc.) and fit new ones if 3. Tighten the screws (4) to 3 Nm (26.5 lb-in) ±10%. necessary. 4. Plug electrical cable into control unit. 5. Install the heater (see 8.7.1.2). www.webasto.us Webasto Product N.A., Inc.
  • Page 40 REPAIR THERMO 90 ST 1 Sealing ring 2 Circulating pump 3 Clip 4 Screw (2) Figure 25: Replacing the circulating pump Webasto Product N.A., Inc. www.techwebasto.com...

  • Page 41: Replacing The Temperature Limiter

    2. Put on the protective cap (1) and secure it with the clip (2). 3. Tighten the clip to 1 Nm (8.8 lb-in) ±10%. 4. Plug electrical cable into control unit. 5. Install the heater (see 8.7.1.2). www.webasto.us Webasto Product N.A., Inc.
  • Page 42 REPAIR THERMO 90 ST 1 Protective cap 2 Clamp 3 Temperature limiter 4 Heat exchanger 5 Round sealing ring 6 Temperature sensor Figure 26: Replacing the temperature limiter and temperature sensor Webasto Product N.A., Inc. www.techwebasto.com...

  • Page 43: Replacing The Combustion Air Fan

    5. Complete the work on stripped-down components (see 9.1.1). 4. Install the heater (see 8.7.1.2). 1 Combustion air fan 2 Screw (2) 3 Shaped sealing ring 4 Burner head 5 Control unit Figure 27: Replacing the combustion air fan www.webasto.us Webasto Product N.A., Inc.

  • Page 44: Replacing The Burner, Flame Monitor And Glow Pin

    (4). Tighten the screw to 3 Nm (26.5 lb-in) ±10%. 7. Install the combustion air fan (see 9.2.4.2). 8. Plug in any electrical cables removed from the control unit. 9. Install the heater (see 8.7.1.2). Webasto Product N.A., Inc. www.techwebasto.com...
  • Page 45 3 Burner head 4 Washer 5 Screw 6 Glow pin 7 Flame monitor 8 Bar 9 Insulation 10 Nut (2) 11 Grommet 12 Grommet 13 Grommet Figure 28: Replacing the burner, flame monitor and glow pin www.webasto.us Webasto Product N.A., Inc.

  • Page 46: Replacing The Burner Head

    6. Complete the work on stripped-down components 4. Fit the combustion air fan (see 9.2.4.2). (see 9.1.1). 5. Install the heater (see 8.7.1.2). 1 Burner head 2 V-clamping collar 3 Heat exchanger Figure 29: Replacing the burner head Webasto Product N.A., Inc. www.techwebasto.com...

  • Page 47: Replacing The Heat Exchanger

    6. Install the circulating pump (see 9.2.1.2). 6. Remove the burner, flame monitor and glow pin 7. Install the heater (see 8.7.1.2). (see 9.2.5.1). 7. Remove the burner head (see 9.2.6.1). 8. Complete the work on stripped-down components (see 9.1.1). www.webasto.us Webasto Product N.A., Inc.
  • Page 48 REPAIR THERMO 90 ST This page for your notes. Webasto Product N.A., Inc. www.techwebasto.com...

  • Page 49: Product Information

    THERMO 90 ST PRODUCT INFORMATION 10. PRODUCT INFORMATION No new or updated information available at this time. www.webasto.us Webasto Product N.A., Inc.
  • Page 50 PRODUCT INFORMATION THERMO 90 ST This page for your notes. Webasto Product N.A., Inc. www.techwebasto.com...
  • Page 51 (2) years effective at the time of installationor vehicle registration date for Original Equipment installations (OE). This warranty period may not exceed three (3) years from the original date of sale by Webasto. This warranty period may be superseded by a contractual agreement.* *Warranty coverage for Marine and Off-road applications containing DBW series heaters and the CSL Cargo Heaters are limited to a maximum of 3,000 hours of usage.

  • Page 54: Webasto Product N.a., Inc

    N.A., I EBASTO RODUCT 15083 North Road Fenton, MI 48430 Technical Assistance Hotline USA: (800) 860-7866 Canada: (800) 667-8900 www.techwebasto.com Org. 03/2008 Rev. 6/2012 P/N LIT1301498A www.webasto.us...

This manual is also suitable for:

Thermo 90 st b

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