So I put a new t-stat in our Accord. I'm still working on other stuff so haven't gotten it back driveable yet. Anyway, a friend was telling me last night that not only is there a certain way it fits in there(I'm sure I got this right), but that there is also usually a top and bottom to them so you have to rotate it until the top is at the top. I had no idea of this and didn't even look for it. Is there a certain way that this needs to go in? How do I tell what the top is? I'm just thinking I may have to pull this apart again to check it out.

 

If it is an OEM replacement it will have a small pin, or a hole through the outer plate. This pin/hole should be positioned so it is at the top.