Where is the compressor relay located in the Mercedes-Benz Viano?
3 Answers
Mercedes-Benz Viano compressor relay is located in the engine compartment. Introduction to relays: Automotive relays consist of a magnetic circuit system, contact system, and reset mechanism. The magnetic circuit system is composed of components such as iron core, yoke, armature, and coil; the contact system consists of static reeds, moving reeds, contact base, etc.; the reset mechanism is formed by reset reeds or tension springs. Introduction to contact resistance: The contact resistance present between the contacts of automotive relays is mainly composed of two parts: constriction resistance and surface film resistance. The contact resistance of the contacts is related to factors such as the contact form, material properties, and surface processing.
When I first took over the family's Mercedes-Benz Viano, I also encountered this issue. The compressor relay is located in the fuse box under the hood. Just open the engine cover, and you'll find that small black box, usually near the battery or the corner of the windshield. Lift the lid, and there's a diagram inside—the compressor relay is labeled 'A/C Compressor' or 'Klimakompressor.' The position might vary slightly depending on the model year, but it's mostly on the front right side. Remember to power off before working to avoid short circuits—turn off the engine and remove the key. If the relay is faulty, the AC won't work—no fan, no cold air. Replacing it yourself is simple: take a photo of the original position, remove the old one, and install the new one. The relay model is listed in the vehicle manual's page number. If unsure, don't tamper—electrical issues can be complex and might damage other components. I recommend checking the manual first to confirm the exact location. Wear gloves to prevent static before working—safety first to minimize accidental contact risks.
As someone who frequently DIYs car repairs, locating the compressor relay is quite straightforward. For the Mercedes Viano, it's usually in the cabin fuse box—just pull open the small drawer under the steering wheel to see it. There's a cluster of relays inside; refer to the diagram to identify the one corresponding to the compressor, often labeled 'R' or 'AC Relay.' Always disconnect the negative battery terminal before starting to ensure zero electrical current. A faulty relay means the AC won't work and remains silent. You can test it: if there's no 'click' sound when turning on the AC, that's a clear diagnosis. While sometimes located in the engine bay, it's more commonly found inside the cabin, making it beginner-friendly. The steps are simple: minimal tools, a bit more patience, and the exact location diagram can be downloaded from the manual online. After replacing the relay, restart and test—if the cold air returns, you've succeeded. Always clean up after working, leaving no components behind, and keep records for faster troubleshooting next time.
