98 Caraven electrical outlet just went out

Hi, 12 v convenience (cigarette lighter) outlet suddenly not working. I have a 1998 Caravan, and I was using a small air compressor for tire pressure when it just quit. I've used it many times before with no problem, and the outlet only works with the engine running. I tried a couple of other things in the electric outlet and nothing works. The rear outlet is also out. I checked all the fuses, and they all look good. The manual doesn't mention which fuse controls the outlet. I'll probably have to have it looked at by a pro, but what should I be expecting to hear that's wrong, so the repair guy doesn'y give me the run around. I know there's a relay box with more fuses under the hood, but I don't want to fool with those on my own. When I first bought the van, used, 2 years ago, the outlets seemed to be not working, then the next day, the started working on their own, and stayed working until today. Thanks for any advice.