1999 Ford F150, 4WD, 1/2 ton
5.4 liter engine

When I turn off the truck and take the key out, the radio and dash lights all shut off, but the fan is still on. I tried just turning it off, but the battery was still dying. My mechanic said that's because whatever it is that's not working properly is still sending out power and it's draining the battery. But when I pull the fuse that powers the fan, then the battery doesn't get drained, and I just poke it back in before I drive and everything's OK.

Someone please enlighten me to what the problem is so that I may have it fixed.

thanks.

 

sounds like the contacts on the fan motor relay are welded closed. a new one probably costs between 5 and 10 bucks.

 

Is this the fan for the heater Ac blower?

If so i don't think it has a hot on it at all times. If you change the speed selector does it slow & blow harder as U change it?

 

I had the relay replaced allready and it still the fan does not shut off.

It is the fan that blows heat and AC.

And yes it does increase in speed when I adjust fan speed. Please, let me know if anyone has had and solved this problem before. Thanks

 

all I have available right now is the 2000 wiring diagram. I ASSume it is similar...

 

I cannot read that to even try to help him, but from what i can make out is that the relay is controlled by the Function switch & in the off Position it should not make contact. So grab a Test light & follow the relay points. Engaged 3 Should show Hot. The Control wire from the Function Switch & the Supply wire from Fuse. The output line to the motor. If the relay has been replaced i would pull whatever fuse that is that supplies current to the function switch & see if it shuts off then. If so I would think the contacts in the switch were bad. The Low Med high switch is obviously working correctly So the ground is not a factor.

Could someone tells us what the box under the 053-001 Heater line is labeled?

 

Lost some resolution uploading to gallery. If the fan shuts off when the function selector switch is put in the off position, then the function switch is getting power all the time instead of only getting power when the key is in the run position (so the problem is upstream from the selector switch). If it does not shut off, then the new relay is possibly bad or the circuit that energizes the relay is shorted to hot somewhere (problem downstream from the function switch)...