1996 Chevy Lumina engine running hot

I bought a 1996 chevy lumina which I thought was a good car. No leaks, test drove several times prior. Not an hour after I had it I stopped to get gas and noticed fluid just pouring out of it. Drove it half mile to repair shop and was informed the radiator had busted. Had a new one installed and mechanic said it was still running hot. Said maybe it needed a coolant sensor. Had that replaced and was assured it was fine but car still running hot. Called mechanic and he said that 1 coolant fan doesn't kick on until 225 degrees.I feel that the car overheats because the gauge gets close to 260 degrees, which is the HOT tepm. AFRAID TO DRIVE! I can't tell if the fan works at all. The air conditioner doesn't work in the car, so I know that fan #2 won't work because of that. What should I do? Can this be fixed? Would an A/C compressor fix if installed or can a rig a toggle switch resolve these issues? I'm desprate. Single mother who purcharsed car with last of $$$ PLEASE ADVISE, THANKS!