Outside air temperature display fluctuation

Hi all, I'm hoping someone else has experienced this oddity and can point me in the right direction to solving this. The problem is the outside temp display on my console is initially correct but in longer drives, 5miles or more, the display slowly increased in temp. Which I ignored initially, until the heater setting was lower than the false outside temp display, when my aircon would start blowing cold, which would continue doing so until I switched the system off. Not ideal. I have checked aircon fluid and that's ok. The compressor runs, and the fan is fine. Possible sensor or fuse ,certainly looks electrical and this is where ok am at a loss and reaching out for any suggestions.
I am looking forward to any advise.
Thanks

 

I suspect a dodgy external temp sensor or a bad connection to it.
I took my passenger side mirror off (on a 307) and the external temp display was just dashes becuae the BSI had no information to work with. When I refitted the mirror and reconnected the wiring to it the display returned.
Where the sensor is on your car (a 2008?) I have no idea but if you can find it and initially check the connections through to the BSI, a squirt of WD40 on the connectors etc, you might resolve it.
If not try a new sensor.