Seat Altea AC blowing warm air

Sounds familiar. I had a similar issue with my Altea's climate control. Check the flap actuator for the rear vents, could be a faulty connection or a broken wire. Have you run system diagnostics to confirm?

Thanks for the tip! Where exactly is that flap actuator located, and what kind of system diagnostics did you run? I'm a bit of a newbie when it comes to car HVAC systems.

Yep, it's almost certainly the flap actuator connection. Unfortunately, I didn't do the work myself; a mechanic friend helped me out. He mentioned that the error pointed directly to that component. The diagnostic tool showed an open circuit on the flap actuator control line. If you're not comfortable tracing wires and testing connections, I'd recommend taking it to a workshop. They'll be able to pinpoint the fault quickly.

Thanks for the help. Took it to a workshop, and you were spot on – faulty connection to the flap actuator. They sorted it for 95€, and the AC is ice cold again. Cheers!