JUNCTION BOX ISSUE

Good afternoon Everyone, Name is Justin

I have a 2008 Ford Mustang. My issue is the AC CONTROL HEAD has no power. Bought a new AC CONTROL HEAD, that wasn't the issue. I had water coming in on the driver side floor board for a long time. Was able to fix that problem after weeks of looking and research. I wanted to ask could the Junction BOX be the issue as to why my AC isn't coming on? I took it to a AC SHOP and they told me control head first bought that it wasn't the issue and he thought the only thing it could be was the Junction box? I have started looking at prices and is very expensive. If I buy a new box can it go directly into car or does a professional have to install it? Are there any way to look and see if the JUNCTION BOX is the issue. I have checked every fuse and there is some corrosion but all fuses are good. I need some help with this as I am at whits end on what to do next.

Thanks
Justin