This is a problem I recently experienced & thought I would share the fix. After researching the problem I decided it was the electric module linked to the ignition switch. When I when to replace the switch I wiggled the plug on the back to make sure I was getting a good connection & re-seating the plug fixed the problem. I did not have to replace anything. YEAH!!!!

 

So your issue that your instrument lights didn't work, the gauges didn't work, nor did the AC, but the fan was only on high speed? Is that right?