Have 11 year old refrigerator that was not cooling down to set temperature. Freezer was at 20 and refrigerator was at about 50. Door indicated temp said set temperature was achieved(as previously discussed that indication is meaningless). After the usual recomended actions, defrost, temperature sensor checks, and visually inspected circuit boards, I recharged the "freon" cooling system using a bullet valve and pressure gage procedure I got from the internet. Initial gage reading showed a very low coolant reading(high vacume) added coolant to a 2 psig level and refrigerator now runs normally. It's been 3 weeks and continues to cool normally, if there is a coolant leak in the system it's not a big one. I'm optomistic. Can always add more coolant if i have a problem in the future.
Condenser coils were very dirty (probably inefficient), looked at owners manual and there is no periodic requirement to clean them, should be. Got a set of "bottle" type brushes at Harbor Freight for $5 worked great. Good luck to all.