1999 Century Heater control Trouble

Hello
Does anybody have a clue why my heater throws heat on the drivers side and cold air on the passenger side. Sometime I get heat from both sides, but more often cold.
thank you

I am wondering if you ever found resolution to this issue? My father's 1999 Century is having the same issue.

If you did, I would love to know before he takes it into the dealer.

cris@thenewcomers.info

Advanced thank you,

Cris

No never found the problem for this replace all the intake gaskets and it seem to help I get more heat now but sometimes it gets cold again.