Heater not working

[Mimster]

Why wont my heater work in my 2001 gmc yukon .Can't get no heat . And sometimes my ac stops blowing cold and starts back.

 

[Doubeleive]

disregard what he says about the flappy noise, the first actuator he points out would likely apply if you do not have any heat

 

[Mimster]

Climate control won't switch to heat. Keeps blowing cold. When I turn to defrost the ac light goes off.

 

[Mimster]

disregard what he says about the flappy noise, the first actuator he points out would likely apply if you do not have any heat

Thanks. I will check it out.