Heater problem

[BLKHOE05]

ok guys so before you go yelling at the noob I did use the search feature and couldn't find anything directly relating to my situation. So just like everyone else when I get in my Tahoe after being warmed up of course I turn the heat on and blows nothing but cold. Blend door actuators came to mind as I have heard lots about that. Anywho my heater actually starts working when I start driving and then goes back to cold when I stop at a light. Any ideas? Could it still be bad actuators?
Thanks

 

[big_b_in_PA]

Water pump may be going bad, air bubble in your system, system needs a flush. I'd say check all those out as they are going to be your culprits.

 

[BLKHOE05]

Ya I haven't found the problem so to speak but I figured out why the heat was acting up. Apparently I have a coolant leak and was down on coolant by a gallon so I filled her back up and it works like a charm. Now to figure out where it is going

 

[big_b_in_PA]

I'd say you definitely had an air bubble then, I didn't ask about the level because I had figured you already checked that. As for the leak, check around the weep holes in the water pump, all your hose clamps ect For leaks. Check the oil to make sure it's not a milky color, if it is I have bad news for you, head gasket issue, or worse. Most likely it's going to be something simple and relatively easy to fix.

 

[BLKHOE05]

ya the oil looks fine and originally I looked at the reservoir and it looked full but I didn't realize that dexcool stains the inside so it always looks full. And I am not seeing any puddles so its gotta be burning off somewhere.