355 a/c evaporator

My 1998 355 a/c evaporator housing has a part that looks like a divider "loose". Aparently this part either fits against the part of the evaporator housing where the blower unit is or maybe this part should be placed to direct the air flow. Could anyone please advise how should this part be positioned? Although the A/C works very well, I have noticed that the windshield does get "foggy" even though the controls are set to direct air only through the dash vents.
Any helpful comments will be appreciated.