Rear Heat in a 2004 Yukon

[ssteinbach]

I have a 2004 yukon and the rear heat only works when the car is in motion or when I rev the engine while parked. When stopped at a light or idle it is considerably cooler (not cold). I did have to replace the hot/cold actuator for the rear unit, and I do have a slow coolant leak. I keep the coolant tank topped off until I can get the radiator replaced. The front heat works great, and temp gauges seem to read fine.

 

Any suggestions?

 

Shane