To add on to what Bill says check those fuses for loose end caps. I had one that looked good but was old and things would mysteriously not work and then work again occasionally. It was not blown but when I went to pull the fuse one end cap easily came off in the fuse holder so I assume was making contact most of the time. That fan fuse at least on my 68 has a lot of stuff running thru it and would get pretty hot before I put in new Coolcat fans that drew less current than my tired originals.
David Barnes
68 E-Type FHC