I just recently bought a 1984 Firebird Trans Am 5 Speed 5.0 HO. It has 71000 orig miles on it and it has been sitting for a few years.
Anyway, I was driving the car down the road and the alternator belt broke ( small belt that is on alt, water pump and crank) So I replaced this belt and filled up the radiator with antifreeze and started it up. It continued to heat up but temp gauge did not indicate this. Antifreeze was circulating correctly and everything appeared to be fine. I then realized that the fan was not coming on at all except for like 5 seconds when key was first turned on. I wired fan direct to battery and it fixed the issue. My question is, what would cause the fan to only come on briefly only when key is first turned on but not as car heats up? There were two fan wires that ran into the top corner of firewall on drivers side that I disconnected to wire directly. What parts should I replace and where are these parts located? Would the thermostat being bad cause this? Thanks for all of your help

 

Additionally, A/C is not hooked up and does not have belt on.