I had the same problem, what I did is top off the reservoar about max and a bit more. disconected the hose and puled it up high, as soon as coolant whent out off the heater core I put the hose in not all the way, I let it drip out and then I put it back. I put the cap back on the reservour and started the car, let it hit up just a bit, the heat sensor just started moving, I turned on the fan in the cabin, put to full, also heat on full reved it up to 2.5K, to 3.0 K, 3.5K, 4.0K, 4.5K and final 5.0K this is how I do it, as soon as it starts blowing heat I reav it againg and thats it.

The bliding I did when its cold. but as soon as it started blowing hot I turned off the engine let it sit for like 5-10min and check the level again, it usually goes down.
Hope it helps and does not confuses.

 

So you left the bleed hold open until the heater was hot?

 

Ok I tried and same problem. It might even be worse now. I have an appt. at 1:30 and for 70 dollars they are doing a full collant flush, so this should fix my problem. Hopefully!

 

So what did you find out about the heater core?

 

Did you ever get your heater working?