Car won't start periodically

I have a 1993 Chevy Lumina, 3.1 engine, with 69k miles. Lately and maybe twice a week after I drive it,then shut it off and try to restart after a few minutes it won’t turn over. Maybe a hour later when I try it again it will start right up. I have also had one instance when it lost power on a steep grade but kept running. I had a diagostic done on it at the dealer and no trouble found. Tonight when I tried to start it, it wouldn’t start but the fan came on and all sorts of clicking sounds under the hood. After trying it a couple more times it fired up and seems to run fine. I just can’t trust it not knowing when it might not start again and the dealer didnt have a clue. Please help!

I suggest removing the battery cables from the battery and cleaning the cables and posts. You can buy a battery cable/post cleaner at any auto parts store. Make sure the connections are tight when you replace the cables. I would also have your battery checked and the charging system tested. You can usually do that at a major auto parts store. If this fails find a good mechanic and they can get things right in no time.

Also slit the coating on the red battery cable 2-3 inches to look for green crud in the cable, it could cause your trouble.