sensor

I have 1996 freightliner with 3176B cat had head gaskets replaced this winter noticed this spring my engine fan not working/manual switch neather. Looked at wiring got 5 wires that come to the front and hook to a thermo switch 2 on one side 3 on the other side with screws there is another wire that comes through the passenger fire wall and hooks to a sensor about for inches back from the other sensor now when I turn the manual switch on I have power there but that is the only wire on there,so I was wondering if those wires could have been hooked up wrong if so what would be the right conections. also my air conditioner not working eather witch I think is tied into this. any advice thanks