Wiper, A/C and horn switches crossover

I have a 2000 Dodge Neon. The car runs fine but the electrical seems to be possesed. I just purchased it from a local private owner. The windshield wipers did not work so I found that the fuse was blown. I replaced it. Everything seemed fine until I turned on the A/C and the wipers turned on. Then I tried the horn and the horn did not sound but the wipers turned on. So, I changed out the multi-purpose switch which included the turn signal and wiper swithches and it did not help. I noticed that the electrical harness connector that went into the back of the switch looked narly so I replaced the connector with a repair kit and that did not help. I have check of the fuses and relays. I cannot find any grounds or wires that could be rubbing. I am out of ideas and do not want to get charged more than the car is worth to have the problem looked over. Someone suggested that it might be the computer. At this point, I do not want to replace that unless it is a strong possiblilty. Anyone have any other ideas?