Heater control does not work

either your control board for the climate controls don't work, or it could be something as simple as the turn knob on the control board, usually they just pull straight off. if there is any damage on that your controls would not work. but if its not that I think it would be the control board itself

I was messing with fuses and heater shut down and the 4 by 4 control panel

I was messing with fuses and the 4 by 4 control and heating system shutdown

5/10/23 I realize this is a new post to a very old post but...... I had the same problem with my 2009 Hummer H3T. My fix? It was the heating and air conditioning blower motor resistor. There was a recall concerning this problem. GM knew about it and issued a recall. I bought my Hummer used and it had already "used up" that recall as it was only good for one time. I thought it was a bit of a bear to replace but I did it. I got the part from my local Chevy dealer and paid dealer prices of course - as I remember about $55. I am now (4 years later) having the same problem. This time I purchased two from Amazon - Genuine ACDelco for $29. Part number is GM 10397098 - search Amazon for GM 10397098 and it pops up. There are videos on YT. I hope this helps someone (-:

take negative off the battery....while changing the electrical parts.....