Blower Relay Location
 

Hello everyone,
I'm new to this forum and will try to be as detailed as I can. Please be patient with me.
I have a '03 F150 4.2L and my blower stays on after I shut the engine off and remove the key. I believe the blower relay is stuck, but I can't seem to find the aux relay box #4. Can anyone help by telling me EXACTLY where it is. I have a Haynes manual and it doesn't mention it and the original owners manual doesn't either. The only way I even know about this box is because at the auto parts store, their computer says that the relay is in this box "behind the dash". Anyone out there able to help? I appreciate all of your help in advance.

the blower motor relay is under the dash on the driver's side.
If memory serves me correctly ( which is about 65% it seems today ) it is just to the right of the steering wheel column.

Same relay block as the flasher.

For your symptom, you might want to do a search on Wet GEM.

sounds like you have a water leak on the windshield, and water is getting into the CJB ( Central Junction Box aka cab fuse panel ) and getting the GEM ( Generic electronics module ) wet.
The GEM is bolted to the back of the CJB.

You might have signs of water damage either where the carpet ends up on the firewall, or the better sign is water at the floor by the kick panel on the driver's side. If you pull the kick panel, you might see rust and the carpet might still be wet.

Few threads on this topic. If you can get the truck into a garage, open the doors and use a space heater or fan to dry out the cab of the truck.

might want to have the windshield resealed ( or replaced if bad enough ) to stop it from happening again.