11 year old maytag frig, freezer not keeping real cold.

How clean are the coils under the unit? If the coils are dirty, and I bet they are, then spray them down with a spray cleaner and wash them off, along with the fan blades with a light spray from a hose nozzle. Then vacuum up with a wet-vac. Dirty coils will kill the compressor and if they have been dirty for a long time the compressor could be bad by now.