No High speed on Blower motor

More than likely this is a blower motor resistor. I am including a couple diagrams below on how to test and replace the resistor.

Here are a couple guides that will help with testing the resistor and then replacing the motor if the resistor tests okay:

https://www.2carpros.com/articles/how-to-check-wiring

https://www.2carpros.com/articles/blower-fan-motor-works-on-high-speed-only

Please see the info attached on how to test the resistor and then replace it if it fails. Again, if the resistor is okay then the motor is most likely the issue and needs to be replaced.