Check your blower resistor first.
The blower resistor has a fuseable link in it.
Its located on the plenum under the dash below the glove box.
It has an electrical connector going to it and is held in with
two or three screws, Easy removal and most posably the problem.
Its in the center of the pic below.
The electrical connector is mostly shown.
This controls low medium and high speeds and is cooled by the airflow
in the plenum.