95 t bird fan problems

my friend had the radiator fan on his 95 t bird go out recently so i replaced it for him with a fan from a junk yard ( i told him to get a new one). so after i installed it i took it for a drive and everything worked fine. a few hours later he went to drive it and it wasn't working again. i was wondering if anyone had any ideas if there could be something wrong with the electrical system or what the problem might be.

The fan turns on at a specified temperature. If the sensor in the block has failed then the fan won't turn on. Have you tried applying 12V to the fan to see if it works? I think, but not positive, on a '95 the fan will also run if the air conditioner is turned on.

ok, the fan works when the A/C is on which is enough to satisfy my buddy, but i still want to make it work the way its supposed to. i know its not a thermostat because we have replaced that already(twice actually, he screwed it up the first time) any idea why the fan doesn't work on its own?

It isn't the thermostat that is the problem. I said the sensor in the block, (Engine Coolant Temperature) ECT sensor, to be more precise. It is located near where the top radiator hose is connected to the intake manifold. Go to your auto supply store and ask to see one so you know which sensor to remove and replace. If he is lucky that will be the problem. If not it could be the control module. Check the connections at the sensor to be sure there is a good clean contact between the plug and sensor before spending money on a new one.