VW Atlas Defrost System Failure: Heating Coils Dead

Speaking from some experience, I had a very similar issue with my 2021 VW Tiguan last winter where the window demister and defroster stopped working completely. After multiple attempts to resolve it myself, the diagnostic revealed a heavily discharged battery causing electrical system issues. The window heater and defroster repair involved replacing the battery and checking all heating coil connections. Total repair cost was 290€ and took about 2 hours at the workshop. Since the fix, all heating functions have worked flawlessly. The symptoms you describe sound very familiar. A failing battery can cause various electrical issues, including problems with the heating system. Before proceeding with any repairs, could you share: Does your car have any other electrical issues? When was the last battery replacement? Are there any other warning lights on the dashboard? Does this happen only when the engine is cold? These details would help determine if your Atlas is experiencing the same battery-related heating issue I encountered.

Thanks for the response. After my last service at 78000km, the issue started appearing intermittently. The thermal window system worked fine before that. To answer your questions: The battery is original, no other electrical problems noted, and no additional warning lights. The defroster malfunction occurs regardless of engine temperature. I checked the voltage at the heating coil connections as suggested by the manual, readings seem normal, so I suspect it might be a control module issue rather than a battery problem. Would you still recommend getting the battery tested first, or should I look into the control module right away?

Based on your voltage readings being normal, this does sound different from my battery-related thermal window issue. Since the problem started after your service, I would suspect a possible disconnection or damage to the auto defrost control module during maintenance. In my case, even though the heating coil connections showed proper voltage initially, the intermittent failures were clearly linked to the battery. However, your symptoms point more toward a control module malfunction, especially since: The issue started right after service, All other electrical systems work normally, The window demister fails consistently regardless of engine temperature A control module diagnostic would be the logical next step. When my Tiguan had similar symptoms later on (after the battery was replaced), it turned out to be a faulty connection at the control unit. The repair cost was around 180€ for diagnosis and resoldering the connection. I would suggest having the control module tested before replacing any parts. The car defrost system has multiple potential failure points, and proper diagnosis will save both time and money.

Thanks for following up on my Atlas heater problem! Your experience with the control module issue seems more relevant than the battery theory, especially given my normal voltage readings. I will schedule an appointment to have the window demister control module tested. Since the auto defrost system started acting up right after the service, I will also mention this timing to the technician. This could help them trace any possible connection issues that might have occurred during maintenance. The 180€ repair cost you mentioned for the control module fix sounds reasonable. Hopefully my heating coil connections just need resoldering like in your case, rather than a complete module replacement. Will update once I get the diagnosis results and know exactly what is causing the defroster repair issues. Thanks again for helping me narrow down the likely cause.