2000 tahoe heat problem

[wild bill]

After driving for 2 or more hours, if heat control is at max temp, lose all control of panel as far as mode and temp control, like blend door is stuck open on heat. If I stop for 20 minutes to eat, it will work fine for months, until it decides to act up again. Any help would be appreciated.

[johnsongp]

I am having the same problem with my 2001 Silverado. Did you ever find out what it was?