Hi @velezgmario ,

It appears as though the blower motor resistor may be starting to fail.

Once it fails completely then the fan will only work on the high setting.

Here’s a link to a video that shows how to replace the blower motor resistor in a 2006 Ford Explorer. Not your model I know (couldn’t find a video for your model year range) but hopefully it is still good enough to be of some help.