My car is a generation 1 126 and it has a diverter flap that makes some or most of the air bypass the heater core and directs the air to the upper center vent. It is used when it is in A/C mode. I don't know about the generation 2 126 like yours. If it has this diverter flap, it could cause a problem like you are having. Anyone else know if the generation 2 has this diverter flap? In defrost or heat mode it should not be diverting past the heater core.

Paul

__________________
84 500 SEL (307,xxx miles)