2007 GMC Yukon XL - heaters blow cold with coolant warning

Vehicle says coolant low add coolant the weird thing is when the message pops up my heaters change and start blowing cold only on the drivers side

The vehicle is accurately telling you that the a engine is in danger of overheating. The heater is confirming that your engine is overheating. If you don’t take it in for repair you will probably lose your engine.

But coolant is full no leaks new water pump and thermostat and its intermittent

There very well could be air in the system from when these parts were replaced. This is indicated by the cool air coming from the heater. The coolant system should be bled.

The overflow bottle is full,
But how about the radiator itself ?
Have you removed the radiator cap and checked?

No radiator cap just cap on reservoir gonna drain and refill fluid today and see if maybe I have air in the system does anyone know where the coolant level sensor is on this car it a 2007 gmc yukon with a 5.3 it is not in the reservoir tank I checked