Cold air sensor fault?

[NickT]

I've been checking over my car and I decided to look under the "hidden" menu on the dash under option 6 to check out values for the air-con. I noticed that the cold temp sensor was reading -5 going to -9 at one point! The hot temp was showing 50 degrees and the ambient was showing 28. I'm guessing the hot and ambient are fine (the car was hot at the time) but the cold must be wrong!

Is this likely to cause the car to run badly due to thinking it is colder than it actually is? Where is the cold air sensor?

Is this going to affect the air-con at all? At the moment the compressor doesn't kick in and I'm not sure why, I know in some modern cars the air-con doesn't switch on if it is too cold outside (wifes Leon for example), I doubt this is the case here though especially when there is an ambient sensor.

Any advice is greatly appreciated.