Sounds to me like the blower motor resister has failed. The blower speed is controlled by a set of resisters. The more resistance the lower the fan speed. When the resistors burn out your blower motor will only work on high. So, as you increase the speed of the fan it goes through a resistor smaller than the last. The last speed or "High" does not go through a resistor at all and gives the blower motor full 12 volts DC. Because of this it will only work on high.
Most are under the passenger side dash. Here are a couple of pictures of what yours should look like.
There should be a couple of screws holding it in place with a 4-cavity plug. Sometimes it will be hidden with a piece of trim or plastic covering.
Hope this helps! If you need any more help at all just reply back!
Images (Click to enlarge)
Monday, February 6th, 2023 AT 4:13 PM