Webasto Thermo 90 S-ADR Heater Service Manual

The Webasto Thermo 90 S-ADR is an auxiliary heater fitted to trucks and heavy vehicles, including crane carriers. It keeps the cab and coolant warm when the engine is off or the weather is bad. When it won't start or lock into a burn, the people who reach for a workshop manual are the ones fixing it in-house, usually after warranty, and they want test steps and replacement procedures in front of them.

What this manual helps you do

• Trace the heater circuit using the circuit diagrams, including the Thermo 90 S-ADR 24 V system with switch and no power take-off.
• Follow the function tests to see whether the heater is running as it should.
• Diagnose problems from the general fault indications, with visual checks of the burner back wall and the pilot flame outlet opening.
• Replace the temperature limiter and temperature sensor, the combustion air fan, or the burner head.
• Check the installation details: pipe and hose connections, exhaust pipe opening position, and electrical connections.

Who this is for

A crane service technician or rental fleet mechanic who has a Thermo 90 S-ADR on a carrier and needs to repair it rather than swap it. Also useful for independent repair shops and plant maintenance staff working on a used truck that came in with no paperwork.

FAQ

Q: What do I receive and how is it organised?

A: You get one PDF file of 55 pages in English. Sections run from the introduction, function description and technical data through function tests, circuit diagrams, repair, and packing, storage and shipment. The text can be searched and copied.

Q: Which heater does it fit?

A: The title reads Thermo 90 S and ST Workshop Manual. It covers the Thermo 90 S-ADR and the Thermo 90 ST-ADR.

Q: How does it fit the job I'm doing?

A: If you're chasing a no-start, you'd go to the function tests, fault indications and circuit diagrams. If a part has failed, the repair section is where you'd look for the replacement steps. It's the complete manual for this heater.

Pull it up on the bench, find your fault, and work through the repair with the procedures beside you.

Click here to view the preview (PDF)

Models covered by this manual

This service manual is also used for one further Heater model: Thermo 90 ST-ADR. Check the model and serial number on your data plate before ordering.

All Crane Manuals