2000 4.7L electric radiator fan is running until it kills the battery.

Yesterday after driving several miles then setting in the car for about 15 min. with the air conditioner running. I got out I heard the fan running. (For the first time in 15 years.) (Honestly, I didn't even know it had one.) Two hours later I drove it 1 mile from there to home, and it was running again. This morning the battery is DEAD.
As of now it is on a charger. I have pulled the Fuse and Relay from the box under the hood. but have no idea where to go from here.

Again it is almost impossible to miss hearing it when it's running, so I think it hasn't been working since I've had it which is right at 15 years or 110,000 miles.
But I would like to have it working right.

Any Ideas,

Thanks,
Jake

 

try replacing the fan relay, sounds like it is either stuck on or fused and causing it to remain on. My best guess is that the fan has been working fine all these years and you just havent noticed it bc it shuts off before you get out of the truck.

hopefully you get lucky and the cheap relay fixes it!