On my 52 fresh air heater, even when in full defrost mode there was air flow (hot) to the passenger's feet that was uncomfortable (yes, dear). There is a portion of the outlet that is unaffected by the diverter. I cut a piece of tin and bolted through the existing screen to block that flow. As a result I got more air through the defroster ducts and less noise from the passenger seat. The windshield clears nicely, but I still have to crack the vent window to keep the side windows defogged.
