I have a Whirlpool refrigerator model WRF990SLAM00 with the freezer on the bottom. It has not been cold enough to freeze ice cream lately. Also the ice maker is not cold enough to keep the ice frozen. Water runs out with the ice dispenser. I removed the evaporator cover and found a block of ice around the copper pipes that connect to the evaporator coil. I melted the ice with a hair dryer and ran a few tests. The temp sensor tests ok and the defrost heater has continuity. I could not get the defrost thermostat to close using ice water but maybe it was not cold enough. Any suggestions?