Just for future reference, when the resistor goes bad, usually the highest speed is the only one that works. In this case, it was the opposite.
This is how it works. When you select any speed other than high, power is sent through the resistor. Based on the selection, the resistor causes less voltage to reach the blower motor. Thus, the speed is controlled. When you select high, power runs direct (12v) so the motor runs the fastest.
In this case, there can only be a few things wrong. First, the switch is bad and not connecting on the high setting. Second, the blower motor relay is bad and not letting power reach the motor. Or three, we have an open circuit. If it was a fuse or a ground issue, none of the speeds would work.
If you look below, I attached the wiring schematic for the blower motor specific to this vehicle. The first thing we need to check is if power is present at the orange wire right from the switch when high speed is selected. If there is no power, the switch is bad. If there is power, then we need to jump to the blower motor resistor/relay and confirm power is present at the orange wire in at the relay. If it is, you got a bad part. If it isn't, we have an open circuit. You will need to follow the orange wire back to the switch to check for a break in it.
I had to cut the schematic in half to make it readable. I did overlap them so you could follow.
Here is a link you may find helpful:
Let me know what you find or if you have other questions.
See pics below.
Images (Click to enlarge)
Wednesday, April 7th, 2021 AT 8:04 PM