Thanks for all the replies.

took it to an AC specialist and he said he’s replaced a lot of blower motors for these and referred to a TSB that the original motors had burrs or something. Those just referred to parts before 11/2019. Said it’s likely going to just keep happening. Asked about checking electrical of the system but didn’t seem interested. Frustrating.

I just went ahead and replaced the blower motor on my own with an OEM part. It’s been working fine. No rattling noises, No sputtering air, No control issues over the past few days since and that’s refreshing.

Not even sure we’re keeping the car. Went out and bought a new 2025 signature, in part due to this AC issue.

 

There were no reported defects in the blower fan and as of this date no one has actually reported the precise cause of the related noise.
As for a TSB being used by an independent service shop, it is an easy way to get the service .
This noise was reported by both OEM and aftermarket blower/fan replacement. So the obvious it’s not the blower motor or fan.