info screne for aircon

hi there, i need advice,
today after taking my 2,5 td hse 2001 on my first long journey all is well and there is just 1 niggly item, where the gauge showing the drivers and pass, ext temp screne there was a little book with an explination mark on it, now not having the manual i cant reference what that means. is this going to be a serious or a quick fix or is there a simple meaning for this?

The book symbol can mean lots and lots of different things wrong with the HeVAC (He-atving V-entalation A/C) system.

Have you noticed anything not working at all with the system?? Does it cool you ok, is the A/C icy cold, how soon after vehicle start up does it come on??

-Wills