Corolla AC and rear ventilation flap issue

Interesting. I have a Corolla too. I did have a somewhat similar problem a while back. My AC was acting up, and it turned out to be related to one of the flap actuators. Not the rear one specifically, but those things are all interconnected. Did the diagnostic tool give you any specific error codes? Perhaps you could check the cable and plug connection to the rear ventilation flap actuator. It's a common point of failure.

Thanks for the quick response! No specific error codes, just a general indication of a fault with the rear ventilation flap. Where exactly is the flap actuator located? Is it easily accessible, or do I need to dismantle half the car to get to it?

Right, a general fault... Well, in my case, gaining access was not for the faint of heart! I'm not entirely certain about the rear ventilation flap on your model, but considering the symptoms, it's probably best to have it checked professionally. A faulty cable or plug connection definitely sounds like a plausible cause and could be the root of your air conditioning problems. I'd suggest visiting a workshop; a proper system diagnostics is key here. It'll save you a lot of frustration and potential further damage.

Thanks a lot for the advice! I took it to the workshop, and you were spot on. It was indeed a defective cable at the rear ventilation flap, just like you said. Repair cost me 95€ Much appreciated!