well i just rebuilt my 350 tpi and stuck some headers on, now the car never heated up before the headers but it does now, and i dont think headers would make the car overheat. the fan just doesnt seem to turn on, i changed the thermostat to stock 195 F
but i asked the GM guys and they said the switch for the fans are on the intake manifold. but i cant find it. where are they?. also i have found 2 connectors that i do not know wtf they are, 1st one is on the radiator there is a spot for a connector to plug in but no wire anywhere to plug it in to, 2nd there is a connector on the passenger side by the spark plugs that is broken. anyone know what these are? cuz it seems my fans work turn on. and i think those are the problem areas.

 

Well I know the one on your passenger side head that's broken is the fan sensor, so you will need to replace that. There should be a wire that plugs into that somewhere around there. It is most likely the fan not working that is most of your problem right now.

 

The thing you mentioned by the radiator that's not connected could be your fan relay. It's near the side/end of the radiator. And if you didn't remove any wires during your rebuild, then the wire connector has to still be there somewhere(probably hanging under the radiator or inside the fat conduit that runs under there). So if that's it, then that would explain why your primary fan isn't working.

The primary fan is controlled by the coolant temp sensor and the ECM. That sensor is the one the GM guys said was in the front of the intake manifold. It's next to the U-shaped coolant hose that runs from the manifold to the throttle body. But I'll guess you're connected there, and the problem is the relay you mentioned that's not connected.

The other sensor(the fan switch) controls your secondary fan. And like TA5LiterHO said, that's the one between the plugs on the passenger side(that you said is broken). But it wouldn't come on until a very high temp anyway, so depending where or how it's broken, it might still be working, but you probably haven't let the engine get hot enough to findout. You can test it by grounding the wire to the frame. If the relay, fan motor, fan fuse and connector are good, the fan will turn on.

So I'd say you're correct in thinking that the two things you mentioned are what's causing your problems.

 

Right, as soon as you turn on the ignitin, the fan should come on, if you ground out that wire.
I am currently running mine that way until I run a manual "on/off" switch for the fan.
Another way to test the fan circuitry is to turn on your A/C, your fan should come on as soon as you turn it on.

 

I the sensor in the radiator tank?? If do then it probleyis an aftermarket radiator and a low coolant sensor that the car is not equiped with. The sensor looks like a spade connector