Nick, you did not specify if you were using gas or electric for the heat. In my 32V Adventurer when using the electric heat, there is a very loud clattering coming from the outside ac panel .. very loud when outside... but not noticeable when inside. It sounds like something is loose and about to rattle off. I have had it to the dealer a few times and they say it is normal.
When using propane, there is no clattering or noise.