my fuse for the heater gets hot when the fan is on. when i first got the truck the back of the heater controls and melted i got a new control block but the fuse and wires to the fuse is getting hot when i turn the fan on the faster i turn the fan to run the hotter it will get. i was wondering what the problem might be

 

Common problem. The wiring gage is marginal at best. As you've seen it usually fries the switch and or fusebox. Pull the blower mtr. and make sure it turns free, and I mean really free. I've tried drilling a hole in the case and oiling the bushings but not much luck. If it's even a little stiff replace it. The wires will still get warm on high even with a new mtr. **** poor design mostly. In a worst case deal you could add a high blower relay [fused also]ala GM style to unload the stock circuit.