Electric fan won't kick on

[RIBoater]

87 2.3
I've tried two sending units and the fan won't kick on when the temp gets too high. The sending unit is really just a ground switch and if I pull the wire and ground it the fan comes one. Two bad sending units? or wrong ones? got one off rockauto the other ebay i believe.

 

[broncojunkie]

Are you just going by the temp gauge on the dash? Are you sure it's accurate? Is the engine actually running hot? You may want to verify it. Also, I've seen folks put a few wraps of thread tape on to keep it from leaking and it didn't allow for correct contact. Just a thought. You should be able to bench test the switch using some water heated on the stove and a meter.

 

[RIBoater]

Thank you for your reply. The needle will peg hot and radiator boil over if sitting idling for too long. I did have teflon tape on it and thought the same thing so took it off. Not sure how to bench test it? it's not like a thermostat you can see open in hot water.

 

[broncojunkie]

You may have to get creative with bench test, but it should be doable. The switch just provides a ground when it reaches a certain temperature. You can use a meter on the ohm setting. When you touch one lead to the wire stud on the switch and the other lead to the body of the switch, it should be open. Heat up the tip of the switch and you should have continuity.

The reason I suggested water on the stove is because you can heat the water and measure the temp to find out how hot it has to be to complete the circuit... that is, if the switch actually works at all.

Another idea is that you may have air in the system and the tip isn't getting submerged in the hot coolant. This would normally happen when the switch is located on the top of the engine. I actually can't recall where it is on the 2.3, so this may not be your problem. I do know these cars have issues with air in the system due to the radiator position vs the upper hose and intake. People have fancy ways to burp it, but I never bothered with that stuff. If i have to top off coolant, I just put a much as I can get in it. Run it till it reaches temp, then shut off. Make sure the overflow tank is in place and keep it full while it cools down. After the first couple drives, I'll keep an eye on the overflow tank during cool down and top off as necessary. I'm usually under the hood anyway, tending to other things.