dim charge light when heater on

I just got a 84 jeep cherokee the charge light comes on very dim when I put the heater on. The light is gets a little brighter as I turn the blower from low to high, but is still very dim on high. I have change the alt.(it was noisy), have also change the blower. When I pulled the old blower out the plastic fan was melted in one spot. The pastic around the resistor pack was also melted.
The resistor on the resistor pack was blurn out so I changed the resistor with one from another pack. The blower works fine, nice and quiet and seems to be moving enough air. I checked the alt with a meter and it is at 14.5v. and the battery is good. This only happen when I put the heater on, it does not happen when I turn the lights on or anything else.
I can't find anything wrong with the wiring and I am not blowing fuses(25amp).
I removed the blower fuse and ran a wire from the battery to the fuse box and tried the fan, the light stayed off. So if I run the heater from the battery the light stays off ,But if I run it through the fuse box it is very dim.
Any Help would be appreciated because this is driving me nuts.

I would look for bad relay, or switch. Someting with in that circuit is drawing too much, maybe wires behind dash grounded together causing the amp draw.

Given the heat damage (no pun intended) of the other heater components, you likely still have a bad wire somewhere as X-11 suggest.

To make sure I understand what you did, you pulled the fuse breaking the circuit. You then took a separate wire, directly from the battery and connected it to the blower's fuse holder (blower motor side) and it worked OK?

If so, all you did was bypass the power feed. The rest of the heater circuit sounds OK. Did you replace the fuse anyway?

http://www1.autozone.com/images/cds/gif/large/0900823d80153ea3.gif

is a link to a wiring diagram. I know it's not your year but it should
point out some other components to look for,

Problem fixed. Having a better look at things( ripped the dash apart) I found the ignition switch and sum of the wires to the switch were melted. Fixed that, made things a little better, but still had a slight glow. The rest of the wiring in the dash is good. So what I did was run a new power (10gage)wire from the solenoid to the ignition switch. This seems to have fixed the problem.