'04 Tahoe NO rear heat

[8100HD]

As it says, my wife noticed yesterday that the rear heat is not working in the Tahoe, fan blows, but no hot air, as you can imagine with temps in the low teens, having cold air blow out of the vents isn't the best thing. I've already checked all fuses and haven't found a bad one yet, just seems like its stuck on A/C. Any help here is appreciated as I'm headed north tomorrow and would like a warm truck.

[spgmeh]

I have the same problem. Did you solve your problem?