doubt it's the switch ,but you never know until testing is done . Do you know what that is ? Automotive systems electrical testing , view a wiring diagram too see what all is involved in said circuit ,an using a DVOM - digital volt ohm meter to test B+ voltage an ground ? Looking at the wiring diagram for the blower motor circuit for your vehicle i see a blower motor relay , a blower motor resistor pack an the blower motor switch . The switch is just a path to ground . If it doesn't work on high speed i would suspect the blower motor relay . View the wiring diagram here
http://www.bbbind.com/free_tsb.html Enter your vehicle information , year , make , model and engine size. Under system click on HVAC ,then under subsystem HVAC controls will come up on it's own . Click the search button then the blue link . Buy a cheap volt meter an test the circuit . That is after watching these videos .
Electric Testing Techniques You Need to Know
The Trainer 32 How To Read An Automotive Block Wiring Diagram
Learn how to test an save money , it's easy ! Is there B+ voltage at the relay .Also check out how a relay work's an how to test .