jelly2m8

If you have an AC equipped Fiero, always turn the system to OFF when you park the car etc. On the AC car's there is an inlet flap on the top of the heater box under the cowl. this will close and seal with the switch to the OFF position. It's not end all but will help debris / rodents from getting into the heater box.

And always, doing that or not, at least pull that blower motor resistor out on somewhat of a regular basis and clean anything out of there.