98XJ with weird heater issue no worky on 3

ok so in the last few weeks i have got this borning plastic smell while the heat is running and the other day i traced it down to the heater setting number 3. Now it is completely off when i put it on the third one. 1,2 and 4 work great with no smells and great power, but no 3. Any ideas or where should i look?? I did take the control panel out of the dash and no burnt or bad wires. thanks

Blower resistor burnt up....
try searching on Blower resistor...
also read this thread...it may help you out...
http://www.geocities.com/chmwatson/FAQs/Jeep/HVAC-fuselink_fix.html

McQue nailed it. Resistor block is toast. I believe it is located under the dash on the passenger side. The link provided is excellent and walks you right through repair. The resistor block is a simple piece that "steps down" input voltage to the heater motor. Less voltage = less blower speed.

Mine did the same but only worked on "high". It took a bit to cross reference the new part number but in the end Autozone got the part in quickly even when the dealer couldn't.

Ireplaced the thermal fuse a couple years ago, very easy. I bought it at Radio Shack, cost about $2.

i was leaning toward that being the culprit but everyone i read about had issues with nothing but high working where mine works everything but 3. Im going to go check it out now and see what i find. thanks a ton!!

ok i figured out some more info but im still not convinced the "resistor" is the issue. I found out why the third position is out. The wire harness and an inch of the blue wire melted(the wire for the third position). So now i need to get a new harness but before i go that far what would have caused this??? Im not sure where this wire goes except possibly from the switch to this resistor block then an output to the blower motor??? maybe im just confused and this block is the whole issue but i would hate to go through the trouble of replacing the harness and this and it happen again in two weeks.. thanks