Not to be the doom and gloom guy, but I think I used that exact one you had and it couldn't keep up in mild 80-85ºF weather. It really needed a shroud to work effectively.

The cost and shroud of the HHR fan made it a very attractive replacement.

For some reason I cannot find a picture showing the previous setup (I know I took one...), but you can see it off to the side of this picture.