Do you have a big stereo system installed? Or a car alarm. If so, something is drawing on the current from your battery and shorting out the fuse. In other words, a positive (or hot wire) is possibly grounding out on the frame or some other location on the car. Check as much wiring as you can possible see. Look for evidence of mice or squirrels. They chew wiring a lot for some reason.
Answers & Comments
Do you have a big stereo system installed? Or a car alarm. If so, something is drawing on the current from your battery and shorting out the fuse. In other words, a positive (or hot wire) is possibly grounding out on the frame or some other location on the car. Check as much wiring as you can possible see. Look for evidence of mice or squirrels. They chew wiring a lot for some reason.