I just finished vacumning the filter on my AC. Started looking at how much rust is on the coils considering it is only 4 years old, and realized it has CAT FUR wrapped around them. The fur gets wet (in the summer) and was like glue. DUH!!! It makes sense with all the fur that comes off of the filter. Heads up! You might want to check and clean you coils regularly.
Another thing, you need to pour bleach (about a cup) in the little hole water drips into from the pan and the emergency drip pan at least once a year. It can save you a lot of misery down the road if it gets plugged....Ask me how I know!!!