S60 outside temperature sensor fault

Hey! Those symptoms definitely sound related to the outside temperature sensor. The car's computer uses that reading for a LOT of stuff – AC, defrost, even the mirror heaters to some extent. Have you checked the wiring and the plug connection to the sensor itself? A damaged cable or a loose connection could easily cause all these issues.

Yeah, I gave the plug a wiggle, but didn't see anything obvious. Where exactly IS that sensor located? Maybe I can get a better look at the wiring if I know where to poke around. Is there a common spot where the wires might get damaged or corroded on these S60s?

The sensor is usually located behind the front bumper, near the fog light or the lower grille. Given your symptoms, I still think the cable or plug is the most likely culprit. If you're not comfortable tracing the wires and testing the connection yourself, I'd suggest taking it to a workshop. They can diagnose it properly and replace the sensor or repair the wiring harness. It shouldn't be too expensive to fix, probably around 95€.

Thanks for the advice! I took it to the shop and you were spot on – turned out to be a corroded connector. They cleaned it up and replaced the sensor, and everything's working again! AC is blasting, mirror heating is toasty, and hopefully no more frozen washer nozzles this winter. Cheers!