Where to start looking for wiring damage/loose connections?

1998 Toyota XLS 90,000 mi. V6

With my outside temp display and a/c & fan not working, I understand that I need to check for wiring damage, loose connections & ground connections. (All fuses are fine). But, where do I even begin looking for this stuff? Would these wires be visible and accessible in the fuse compartments (driver, passenger, under the hood), or would they be hidden inside the dash or other hard to reach area? The more detail you can provide, the better.

Thanks!