WHY DOES HEATER FAN HAVE POWER ALL THE TIME

Hello there, Two reasons: leaking windshield and/or a bad relay. The relay for the blower motor can stay on when it goes bad. It will be under the dash in the fuse box. If you aren't sure which one, you really can just remove them one by one until the fan turns off. You need to test the relay that turns it off. If you have a leaking windshield, the water can run straight into the back of the fuse block, so If your relay is good, you may have some water in there, or other wiring issues.