My "recirculate" valve is definately stuck, although it worked when I took it all apart last year. But I think it may be stuck to the fresh air setting. That little window on the heater is never open. But my defroster doesn't exactly send a galeforce of air over the windshield, even with the blower on full, and the heater doesn't seem to generate all that much heat ever. Can that be the 180 degree thermostat? What blows from the deluxe heater isn't close to 180... The temp gauge shows normal operating temp.
I have gotten used to a foggy windshield. I'll never find any Buick heaters over here.