The 96 Park Avenue Ultra I just bought from my dad recently has now presented me with a heater mystery. I guess it's just desserts considering I guilted a good price out of him while he was in a daze from buying the Jag of his dreams.

The heater hoses are hot, but the heater is blowing lukewarm air (at best) from the driver's side floor vents, but unheated air from the passenger's side floor vents. This happens in auto and manual modes. It seems to have happened all of a sudden. The heater was working fine when i got the car last month.

Any suggestions? Thanks in advance.