NV outside temperature sensor issues

I have an NV as well, and your symptoms sound familiar. The outside temperature sensor is used by a bunch of systems, so if it's giving bad data, it can cause problems with the AC, defrost, and mirror heating. I would guess a bad sensor, or more likely a wiring issue to the sensor. Before replacing anything, check the plug and wiring going to the sensor, it might be corroded or loose. Where is your sensor located?

Thanks for the tip. Where is the sensor typically located and how difficult is it to check the connection?

On mine, the sensor is located near the front grille, behind the bumper. You should be able to access it by reaching under the bumper, or you might need to remove a few clips to pull the lower part of the bumper cover forward a bit. Honestly, if you're not comfortable doing that, I'd suggest just taking it to a workshop. It ended up costing me 95€ once to have them sort it; they said it was a defective plug connection.

Appreciate the advice. Will check the connection, but most likely take it to the workshop. Thanks for confirming it's probably the sensor!