Have you read your manual? it describes air distribution
This is the second time I have replied to one your emails asking questions about items/issues that are described in your manual.
Please read it or get one from ebay or the dealer. You might also purchase a Bentley repair manual from an on-line suppler. It is about $50 or so. It provides many technical answers. The archives are a great help. This question has been asked several times before. BTW, I had to check my manual to see why warm air did not come out the center vents.
That said, the rear vents only blow cool air. They are not heated. My owner's manual even has a picture illustrating where warm and cool air is distributed.

Originally Posted by
Shade Tree
When the heat is on, there is cold air coming out of the rear vents. The vents under the seat blow hot. It seems like a servo or hearer valve. Anyone have any ideas?
Thanks,
1995 525i Auto, M50TU 2.5L, EAT chip, 1/95 build, USA, 205/65/15 tires, ASC+T, HID, lumbar, EC Mirror, BMW Alpine 5 radio with BMW-Pioneer CD Changer, abt 236k miles, Oxford Green/Parchment