About 10 minutes after driving, the heat starts to blow out of the upper vents when the a/c is on automatic. The heat comes out even if the outdoor temperature is mild (55 – 70 degrees Fahrenheit) and the cabin temperature is warm, which heats up the SUV quickly making it very uncomfortable. Turning the a/c off tends to somewhat solve the problem some of the time, however, occasionally hot air creeps through the vents even with the a/c off. The a/c often makes a gurgling sound whether it is on or off. I noticed today (2/3/12) that the back vents are not affected by the problem, so the very warm air is only coming from the front upper vents.
You have a stuck blend door, either the motor is bad or the door is just stuck and needs to be moved. Not uncommon on hondas with automatic climate control.