My cooling fan runs constant. I've just changed the Temp sensor! It's still running? anyone got an idea why.

 

the relay may be shot..

 

Maybe, but the relay only clicks on when the car is started. then only switches back off when the engines cut. Will it still do this if its shot?

 

well let's see... I could be wrong...

but the fan switch is the ground side of the relay, the temperature switch reports to the ECM of the current temps, then the ECM sends a 12v signal to the relay to close and therefore sending juice to the fan... am I right...

so with that being said, if you already replaced the fan switch then you should check to see if your temperature sensor is closed...

 

I'll check , Thanks

 

You are not totally wrong. There is no fan switch on an 86 with single fan (that's all there was). Also, the ECM provides ground to the relay, not +12v.

There is an a/c line on the passenger side frame rail (aluminum) with a 2 wire plug on it (blue and black wires), unplug it and jump the plug terminals. If it solves the fan issue, the fan pressure switch on the line is bad (no longer grounding).

No-A/c vehicles had the blue wire grounded, if the blue wire is left open (no ground), the fan will run as soon as the ignition is keyed on.