Pretty sure that's a temp sensor for the A/C. Pretty sure it has a hard "wire" coming from it, going through into the black plastic case and pokes into the core that's in there...
From memory the GSR (non jap) has a silver/gold wire, where the EVO (or jap spec) has a wire that is coated in a blue rubber or plastic (it's been a while !!).
I'll see if I can get you a pic tomorrow of mine. It may help someone spot the right one for you..
Best bet to find one though would probably be Trade me in NZ!! That's where I got most of my smaller stuff like that for mine from.