S40 AC and sensor error

I had a similar issue with my S40 a while back. Check the air conditioning control unit; that was the culprit in my case. Did you notice any other weird behavior from the temperature gauge or HVAC system before this started?

Thanks for the quick reply! So, if the AC control unit is defective, could that directly cause the sensor error and AC failure? I haven't noticed any odd temperature gauge readings, but the HVAC system has been slightly erratic lately.

Yes, absolutely. A faulty AC control unit can definitely throw off the temperature sensor readings and prevent the AC from engaging. Given the symptoms and your suspicions, it's worth getting it checked out by a workshop. I ended up with a 980€ repair bill, unfortunately.

Thanks for the confirmation and the price range. I'll take it to a shop and have them diagnose the AC control unit specifically. Hopefully, it's a straightforward fix. Appreciate the help!