gen 1 light on with heat

[islandguydon]

The first one on the left is the same operating condition as you discribe. Mine works fine just a large draw on the alt. Check your belts..

 

[epartsman]

My truck is doing the same thing, and the fuse box is eating a fuse a day. It burns them up, melts them and the heater will only run for a little while before this happens. Where do I start looking?
I am going to pull my heater control box to see if that is the cause.

May need a new blower motor. Sounds like water got in it and it is drawing too many amps.

 

[OlBigMC]

The same thing happened to me. Did you figure out what the problem was as well as the fix? May not be related but my CD player lost power the day before.