Air Duct Cleaners

I have a question about cleaning my central AC to prevent freeze up. Half the unit is in a box in the attic?

tiedyedude asked: There is a coil with cooling fins that looks like a radiator. Is this the part that needs the backside cleaned? The backside is not made to be accessible, it is inside a duct made of fiberglass. I assume it must be the cold air return since the squirrel cage blows into a [...]