Oldsmobile/Buick Repair: fan, coolant temperature sensor, temp sensor

Question
The Fan On My 1995 Olds Achiva S will not come on unless I unplug my Coolant Temperature Sensor. I have replaced the C T S with a new one and it still will not work. What could be wrong

Answer
hi kevin.well if your fan comes on when the cts is unplugged we can eliminate a bad fan mtr.the next suspect for me would be the fan relay.the temp sensor and relay both operate the fan when you unplug it you are interupting the ground in essense bypassing fan relay .first turn a/c on or defrosters and see if fan runs.if it runs you have a faulty connection at the relay if not you have a bad relay.check this and let me know if it helps .good luck kevin