[updated:LAST EDITED ON 19-Aug-02 AT 07:45 PM (EST)]In the process of installing a new stereo receiver and while the gauge cluster and bezel was out of the dash I was running the ac in my '78 F150. While check switches and connectors I noticed that the wires and switch of the ac unit was extremely warm. Almost to hot to touch.
Does anyone know if it is normal for the wires and switch to operate so hot? I checked the fuse for the ac system and it is the correct size. It seems like it would require a lot of amps in order for the wire and switch to get so hot.
The charging system seems to be working ok and everything else seems to be working ok also.
I have not done any new wiring yet for the stereo and there doesn't appear to have been any shorts or other wiring done.
The only thing that doesn't work is the lowest speed of the blower motor.

 

It sounds like you may have some resistence in the switch contacts or the connections for the wires. Resistence causes heat (I^2*R). You might replace the switch and check all the connections. If the heat builds up enough, the insulation on the wires can melt and things start to snowball.

 

That's exactly what I was afraid of. The first thing I noticed was the smell of wire melting.