My 1997 2.5 does the same thing after idleing for about 2 minutes. Smells exactky like an uprightvacuum belt burning. Can't smell anything from under hood. It seems to be there when on outside air more than recirculate. I will try it with the fan speed on high, that removes and wire wound resistors in the motor speed circuit. Even my old 94 T- Bird had electronic fan speed control, no heat and no wasted energy. Older GM cars put the resistors in the fan duct to keep them from melting.
Richard.