I started hearing a whistling sound coming out from the return vent for the air conditioner. So I pulled out the filter to inspect it and noticed there was something odd inside the duct. It looks like trash and wasn’t sure if I should remove it.
The duct goes straight up the package unit on the roof.
Best Answer
It's "trash". This is exactly why I don't like flexible air ducts lines and I only use them if I absolutely have to.
Couple of things: