AC question 2005 2720

[coralcruze]

So I believe I have the Colman Mach AC on my roof.

Noticed a slight leak. I would like to take care of it before it turns into a bigger issue.

First can anyone explain to me why TM installed a riser box (not sure what to call it? Or its technical name) And then installed the ac box over that? However seems like the brick molding they used to create that ac box has cracked letting some water in. So I would need to remove the AC and then remove the the lower riser box and rebuild a new brick mold.

Any threads of anyone replacing the Colman Mach AC on this site I could look at?

Thanks.