2000 Chevy Silverado Airlocked?

Opening the degas bottle shouldn't cause an issue. If you are suspect to air in the cooling system, you can bleed the air by removing the radiator cap, and let it come up to temperature. How long has it been since the coolant was exchanged?

I took the shrowd off to look at the radiator. There is no cap, the only cap is on the surge tank. The day before I took the cap off my heat was just fine so it is not the coolant. There was a lot of vacuum in the tank when I took the cap off. My truck temp is running consistent a 190 degrees and all seems well. Both hoses coming from the heater core are warm so it is not plugged. I know there is air in it and don't know how to bleed it out.

WTF am I thinking? Start the engine.
Idle the engine for 1 minute.
Loosely install the surge tank cap. Do not allow the system to build pressure.
Cycle the engine from idle to 3000 RPM in 30 seconds intervals until the engine coolant reaches 99°C (210°F) and the thermostat opens.
Shut off the engine.
Refer to step 3 in order to remove the radiator surge tank cap.
Start the engine.
Idle the engine for 1 minute. Fill the surge tank to 1/2 inch above the COLD FULL mark on the radiator surge tank.
Install the radiator surge tank cap.
Cycle the RPM. Idle the engine to 3000 in 30 second intervals until the engine coolant reaches 99°C (210°F).
Shut off the engine.
Top off the coolant, as necessary, to 1/2 inch above FULL COLD mark on the radiator surge tank.

Done that. I even parked it with the front up in a snow bank so the air would work it's way out. Thanks for the suggestions.

Okay then, we can rule that out. The next step is to determine if the blend door is in the right position. Under the evap case, you can access the blend door. Move the temperature settings from cold to hot and see if the door is opening all the way, and closing all the way.

OK, where is the evap case.

On the passenger side under the dash. You'll see what I'm talking about when you start exploring.