1993 Ford Explorer A/C Heater fan

The heater fan can be changed from under the hood, on the passengers side you will see it disconnect the wiring going to it then remove the three screws that hold it in place. You will be able to gently remove the motor and the fan as one unit.
To cut cost of a new one you should be able to find one at a local jump yard. Match one that cane off the same year and model or they will be able to tell you what ones fit.