No heat from rear vents
 

Doesn't matter which position the hot/cold slider is in, only cold air comes out of the rear vents (the ones on the back of the center console). Could this be a heater control valve? Perhaps the rear control is bad? Coolant level is spot on.

4 zone climate control or no?

No. Just the standard:

http://www.icarpart.com/media/catalo...mage_14751.jpg

How do you have your 2-zone IHKA control panel set? If you don't have the 4-zone (S4NBA auto climate control)...the air duct ( connected to#10 in diagram below) may be transmitting fresh air that has not passed through the heater core if you don't have the AC button pressed (see text highlighted in yellow in info below):

So, in order for rear heat to come out, the AC button needs to be pressed? I'll give that a try on the way home.

Any update? Did pressing the AC button work to get warmed air to come out of the vent at the rear of the center console? Or are you still getting cool air from that rear vent?

Still getting cool air.

servo motor possibly in the ihka airbox? Do you get hot air from front vents?

Sorry, maybe I missed it, but do you get heat out of the front vents?

Yes still getting hot air from the front vents. And the servo motors at least work to change from foot vents to windshield vents, etc.