reviving a crazy old thread because i just did this and thought i'd take a few pics to go along with the info here. my heater only worked on 0, 3, and 4, and i tried replacing the controls themselves long ago and found the problem still remained. i found this thread and almost fixed the coils but instead i ran down to the junkyard and pulled a new used one in good condition off a wrecked terc there.
so as highlander said, remove the glove box (two screws at the bottom). then remove the black air duct (two more screws). i also removed the big white box that sits right behind the glove box because i wasn't too sure what i was looking but you don't need to do that.
here's what you will be looking at by this point, plus the white box i needlessly removed:
this plug with the blue wires clips into the resistor pack that controls the heater speeds. i had already removed the resistor pack by this pic but that's where it lives:
remove the plug and the one screw that hold the resistor pack in place and carefully pull it out. here's my broken one. you can see the two coils for heater settings 1 and 2 that are broken:
here is the new resistor pack next to my fried old one:
(carefully) throw the new one in, screw it down, plug it in, put back the black air duct with 2 screws, put your glove box back on with 2 more screws and it's done. only takes about 10 minutes total, which is even less than it took me to change the light for the heater controls! very glad to have heat settings besides 'off' and 'face melting' again though.