loud popping behind dash. HELP.

loud popping behind dash??

hey guys, recently my ex has been making very loud popping noises behind the dash. Sounds like satan trying to escape from the deep,deep bowels of my dash lol. And before anyones like "use the search bar noob that's what its for" I couldn't find any info on it. I see the blend door is a big problem but hear me out bc my conditions are a bit different and that's why i'm confused.
1. The loud popping occurs with KOEO and also KOER
2. Loud popping occurs with heater controlls off and will pop more frequently with heater controls on. Doesn't change with fan speed.
3. Apperently, people will lose heat or different zones will not work.(defrost, vent, foot, ect) Mine all work. Also rear fan does work
4. Heat and aircon both work.
Im just stumped. Any input would be greatly appreciated.

Air in the heater core

lobo411 said:

Air in the heater core

Click to expand...

Havent opened the cooling system and trucks not leaking any coolant so i dont think theres an air pocket somewhere.

My bet is that the blend door actuator gears are binding and eventually the door will fail.