Heater controls changing

[ElyDuckMan]

Hi All

I have a 2007 GMC Sierra new body style and when I have the heater on it might blow on my feet like I have it set to do but then out of the blue it will change to the body vents and the fan speed will also change on its own. Any idea why this might happen and how to fix it?

Thanks

[tanked_darren]

that's a new one. Usually they either don't move or the blower doesn't work in certain speed or not at all.