So as the title says, i can't figure out why my fan wont turn on. If i let the car sit idling long enough and im not moving, then the temp gauge slowly starts creeping upwards. During this time the fan is not on. As soon as i start moving forward and air gets moving through the radiator the temp goes right back down to normal in a matter of 5 seconds. While driving the gauge stays right where it should, its only when it sits idling for a few mins that it starts overheating.

So basically im trying to figure out why the signal isn't getting to the fan to turn on. i have no check engine lights, and everything so far as i can tell is working properly aside from this, (and my shift linkage issue in a different thread). The only connector that i left unconnected on the engine is a coolant temp sensor thats on the radiator hose neck for the lower radiator hose. I didnt have any plugs left for it. It looks the same as the connector on the head which is where i plugged in the coolant temp sensor because thats where it was on the old engine, and clearly it seems im getting a coolant temp reading, so i'm assuming i don't need that other thing plugged in then.

So at this point i'm gonna look over the wiring in that area of the engine bay. Then see if i can find an ecu pinout and maybe find out which wire goes hot to tell the fan to kick on; or maybe its a ground since i know there is a fan relay and maybe its a ground activated relay.

 

the thing you think is a coolant sensor IS the fan switch the old engine had it on the back of the block yours has it on the thermo housing. get the plug from an obd1 motor and hook it up to the the wires behind your block probably dangling there

 

thank you sir!! that did it