Ambient temp shows 0 even when it's 25 outside

Hi. Anyone know why my temperature gauge says 0 degrees (on the HEVAC screen) when it was a swealtering 25 degrees outside?
It did this on Sunday after I started up my P38.
This meant that the aircon wouldn't run cold. As I drove on the ambient temperature on the screen slowly progressed up to what seemed normal. Then the air con worked fine. Today all is still well and it shows correct temperature.
Could this be the ambient temp sensor on the way out or does this just happen sometimes?
Cheers.

So its dont just me then!

Mine does that most of the time. I find that starting the engine, then switching off after a second or two, then switching the ignition on again tends to sort it out. Sometimes takes a couple of goes, but it works on 9/10 attempts.

I'm hoping it's just the outside temp sensor is knackered, otherwise I'll be looking for a HEVAC unit - which I really don't want to be having to change as it works the rest of the time.

It could be the temp sensor is buggered but if that was the case I would of thought it would stay reading 0*C or something all the time.

Are your P38's within the below VIN range?? If you have the original HeVAC panel and your within the affected VIN range then I should think thats your problem...




If you want to test the ambient air sensor with a multi meter then these are the sensor values - cheaper option than replacing the panel outright if the sensor is at fault.



-Wills

Mine's in the first 3500 P38s built, so it'll be that on mine.

Irritating when it's fine the rest of the time, blend motors etc all behave and the AC is ice cold when that's what I want - unless the ambient thingy plays up.