I have been reading some of the other posts and am at a standstill right now. I have seen this problem where the Frigidaire was working fine and all of a sudden the freezer stopped freezing and leveled out at about 40º. I first vacuumed out some dust off the coils in the back. The compressor is warm to the touch and the condenser fan is working. I took the lower back panel off inside and there was a frost buildup just on the top layer of the evaporator coils and that fan is running also. At first I thought it was the defrost timer and checked the defrost thermostat. I sprayed it for a few minutes with some diagnostic freeze spray and the defrost coil never came on. It ohm'd out good and the end looked a little corroded and cleaned it. After putting it back on, the top layer of the evaporator gets frosted to include the thermostat and apparently at some point, the defrost coil must come on, as it defrosts and the temperature gets up to about 55-60º. The compressor seems to kick on and it frosts up again and goes through the same cycle. It only seems to frost the first row of the evaporator coils. Any suggestions for this type of cycle. Refrigerator side seems to stay at around 40-50º. Temp controls are both at factory setting and turning up colder has no adverse effect. Any suggestions?

You have refrigeration problems for a pro to look at, only pressure gauges and amprobe will show what the problem is.