I need some help . I have a 68 fury factory a/c car. Last week I turned on the defrost mode and nothing/ heat.. Nothing . No fan operation on any speed . Turned on the a/c and it all seemed to work fine . I put a fuse in and had the fan on hi and about 5 min later I smelled something burning which was the solder melting in the new fuse . I turned it off and looked things over and the fuse box had actually started to melt . I changed fan speeds while touching the fuse and it would get very hot on hi speed and I would turn it down or off before the fuse would blow . I also noticed the wires were warm out at the blower motor . So here's what I have done.... Replaced blower motor .. Pulled out the connectors at firewall . Cleaned/ dielectric grease on everything (it all looked good for the age..cleaned the blower motor ground. Put new ground cable on battery and ground to body. Took apart fan switch cleaned and sanded all contacts and confident it's all good . Pulled out blower resister it looked good.also ran blower on hi without the resister and fuse still getting hot . Also disconnected power wire from ignition switch to fuse box and ran a wire directly from battery to the fuse and tuned the fan on hi and it still got hot . I do have a sanden style compresser on the car and a powermaster alt. all this has been on the car for over a year and everything has worked perfectly . It also does this with the compresser unhooked and I checked the voltage at the fuse box and it was in the upper 13v range at fast speed upper 12s at an idle. So I welcome advice.. I am at a loss and just want to get it all working proper again