2002 handicapped Chrysler Mini Van Problem

My father's handicapped equipped 2002 chrysler mini van is having major issues. About 1 month ago he heard a clicking sound from the engine after the car was turned off. When returning to the car, after a period of time, the car was dead-the problem was obviously related to the battery/electrical system. The car was looked at by both his local mechanic and a Chrysler dealer. The battery was determined to be fine and the car computer was replaced-the ticking continued. The Chrysler dealer blamed the fact that the van was converted for handicap use however this wasn't an issue for the 1st 97K miles as a handicapped van! My father has had to disconnect the battery while the van is not in use. Yesterday during a trip to my home the car lost power steering and air conditioning. The trip is about 50 miles and the air temperature was about 97 degrees. The temperature and battery warning light were lit. When I looked at the engine it was clicking. I noticed that the ASD Relay fuse was clicking-I have no idea what that is or means. The next morning we saw that the coolant level was low and we replenished it. When we started the engine and ran the heat the temperature level, within 10 minutes, got very hot and the temperature and battery light went on again. Obviously I do not know what the problem is or if the electrical problems and the recent problems are related. Any insight would be helpful.