1999 Chevy Cavalier cooling fan

[quote:8966d99fbc="Trei"]Engine Cooling problem
1999 Chevy Cavalier 4 cyl Front Wheel Drive Automatic 53000 miles
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The engine was replaced last week (used), their is coolant in there. I picked up the car Saturday, drove it to town Sunday, then work on Monday, Last night when driving the car the temp guage was reading hot and the light was on, The fan didn't engage, I took a wire and spliced the wire to the fan and ran it to the battery for now, (seems okay). Before I did that I took the relay out and replaced it with the heater relay to see if it would work (it didn't), thats when I wired it to the battery. What could it be: Radiator Fan Switch, Sensor, ????[/quote:8966d99fbc]

Sounds like the ground circuit is ok. When buying the temp sender for the fan a quality part such as delco comes with the wire connector because the connecter tends to go bad. I usually disconect the ECT with car running and fan should come on if not problem is from engine to fan but if fan comes on I replace sensoer and connector. Providing if closed cooling system is water tight and all air is out of system and radiator cap must be good.

Before you do anything I would take it back to the shop you had the engine replaced at. And make sure they are not responsible.