I just got my H3 back from the great folks at Reeves HUMMER in Tampa today and they solved the burning wire smell from my A/C vents. It seems that the blower resistor or ballast resistor as we used to call them back in the day was overheating and melting. This part is mounted behind the glove box so that would explain why the problem was so bad when set to recirculate or max. This seems to be a common GM problem after searching the net so if you smell burning wires or the blower fan acts up, you now know what the problem is.

 

KUDOS. Those fireman sure got a nose for a "burning smell"!!