Ac noise in cold temperature

[drewdogg77]

My 650gc makes a motorized like noise whenever the temperature outside is cold through out the AC vents,, its not a watery sound its like a motor is trying to turn but stuck,, whenever the temp outside is about 73 degrees and below... Took it to the dealer and they drained out all the coolant and replaced it, they said its air in the cooling system but the noise is still there... any ideas what this could be????????
I have another appointment on tuesday 12/9/19 one of the techs said it could be the motor for the flap making the noise,, thing is they have to pull my whole dashboard out tho.....