Recently my car (93 tr 2.6) has started overheating ->going from about 1/2 on the temp gauge to 3/4 during city driving. I saw that the radiator fan was stopped and I guessed that was the problem. I shorted the plug that connects to the fan/thermo sensor that screws into the bottom of the radiator and the fan operates. Thinking that the sensor was the culprit, I went and bought a brand new sensor and plugged it in but the fan still does not come on even with the temp gauge going over half way.

Could there be some other reason the fan works when the switch is shorted but not when its plugged into the sensor? Could the radiator be blocked so much that the hot coolant doesnt circulate down enough to trip the switch?

PS. I did a coolant change/water pump replacement before I replaced the switch thinking it was old coolant and a dodgy pump. I did not backflush the radiator during the process and I used red coolant,

Any help would be appreciated

Cheers

Make sure your thermostat works. I had this happen and unfortunately i thought my temp. gauge was lying to me! Turns out the temp. guage was right.
I learned first hand what happens when a head gasket blows.

If its not the thermostat, it must be a blocked radiator. You should be able to check by draining into a clean container, and seeing how much comes out.

Be careful, and don't keep driving if temp. goes near 3/4. especially if it goes above, don't even use the throttle unless your in a life threatening situation (such as a truck tailgating you :S).