AC switch wiring

I need some help. The AC push buttons on my 1994 512TR work intermittently. When they don't work, no evaporator fans, no AC, when they do, cold air blows out of the vents. By accident, I was looking for a blown fuse and I bumped the "I" connector on the driver's side of the fusebox and everything started working. I removed the "I" and "J" connectors, cleaned the contacts and replaced the connectors and all worked well for several months, but now it's back to intermittent and random and the fix above does not work. I want to trace the wiring path to and from the push buttons.

I have tried and tried to follow the wiring diagrams in the workshop manuals, but I can't figure them out (they are repos of marginal quality). Can someone tell me which wire on which connector brings power to and from the push button switch and from there which wire exits the fusebox to the evaporator fan? I would be much obliged, and can then start hunting the problem.