The most common cause of the fan only working at high speed is the result of a faulty blower motor resistor.
On this vehicle, it is located under the dash on the passenger side. You will need to remove the insulator under the dash on that side to access it.
Once that is removed, look upward and you will see the HVAC box. There will be a connector going to the resistor. Disconnect the connector, remove the two screws holding it in place, and remove and replace.
Let me know if this helps. I attached a pic below to help you locate it.
See pic below.
Saturday, April 16th, 2022 AT 10:24 PM