Found system had been frozen over above the top of the evaporator coil and all the way to the compressor. Turned the condenser of at the breaker and left the furnace run to thaw coil. Explained to the customer we need to return when the coil is de-iced. The customer agreed and scheduled for tomorrow between 12-2. Came Saturday and no more ice. Found rusty coil, clogged filter and low on freon. The condenser coil is very dirty, will cause high head pressure and the system will not run efficiently. Installed compressor saver and added 2 lbs of freon to the system. The system should be replaced in the near future. Upstair is cooling at this time.