Webasto Thermo 90 ST-ADR Heater Service Manual

The Thermo 90 ST-ADR is an auxiliary heater fitted to trucks and heavy vehicles to warm the cab and the coolant. When it won't start, cuts out or throws a fault, someone has to get into it. That's usually a technician in a shop or a fleet mechanic with a unit that's out of warranty and no paperwork. This manual is the workshop book for that job, and it covers the Thermo 90 S-ADR as well.

What this manual helps you do

• Trace the wiring using the circuit diagrams for the ST-ADR, 24 V, with switch without power take-off.
• Check the burner with the visual checks for the burner back wall and the pilot flame outlet opening.
• Run the function tests and read the general fault indications to diagnose a heater that won't hold a flame.
• Replace the temperature limiter, temperature sensor, combustion air fan or burner head using the repair procedures.
• Verify the pipe and hose connections, the exhaust pipe opening and the installation position against the specimen installations for a truck.

Who this is for

Independent repair shops, rental fleet mechanics and plant maintenance staff who service heaters in-house. It also suits a dealer technician who needs the function description, technical data and repair steps in one file.

FAQ

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

A: You get one PDF of 55 pages in English, with searchable text you can copy from. It runs from the introduction and function description through technical data, function tests, circuit diagrams, repair, and packing, storage and shipment.

Q: Which heater does it fit?

A: It's written for the Thermo 90 ST-ADR, and the title reads Thermo 90 S and ST Workshop Manual. The Thermo 90 S-ADR is covered in the same book.

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

A: It's the complete workshop manual for this heater. If you're chasing a fault, you have the fault indications, tests and wiring. If you're replacing a part, the repair section walks through it, and the fuel extraction notes help when you're working on the tank side.

Print it, search it, or keep it on the shop laptop, and you can work through the heater from the first test to the last repair.

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 S-ADR. Check the model and serial number on your data plate before ordering.

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