91 maxima radiator fan doesn't work

I'm thinking about buying a 91 nissan maxima, but when we test drove it (from a private seller; friend of a family member) it overheated, and we looked and saw the fluid hose connecting to the radiator was off. So we put it back on and tightened it, but it didn't fix the problem. We looked again and discovered the fan wasn't going. I'm not a car person, so can anyone tell me the different reasons it wouldn't work, and possibly things to try to fix it? If there are simple/obvious things it could be, or inexpensive fixes, I'd like to know before I decide not to buy it, since the car is in great condition aside from this.