The 3 most common part(s) or condition(s) which cause the symptom Refrigerator freezer is cold but refrigerator is warm are listed below starting with the most likely. Check or test each item and watch any available videos.
If the freezer is cold but the refrigerator is warm and the evaporator coils are frosted over, there may be a defrost system problem. Several times a day the defrost heater assembly turns on for a few minutes to melt away any frost or ice that may have accumulated on the evaporator coils. If the defrost heater assembly has burned out, or the defrost thermostat or defrost control have failed the frost will build up on the coils and eventually no air will be able to travel through the coils to provide cooling. The most common cause for this condition is a problem with the defrost system.
RepairClinic Item # 1246
If the refrigerator freezer is cold but the refrigerator is warm, the evaporator fan motor might have failed. Every refrigerator has a set of coils called an evaporator. These are the coils that get cold. A small fan and motor is mounted near the coils. This fan and motor - called the evaporator fan and motor, draws air over the evaporator coils and circulates it throughout the freezer and refrigerator. If the fan fails, the freezer or refrigerator will get much warmer than usual.
RepairClinic Item # 2387
If the refrigerator freezer is cold but the refrigerator is warm, the defrost thermostat might be defective. Several times a day the defrost heater turns on for a few minutes to melt away any frost that may have accumulated on the evaporator coils. In order for this to work, the defrost thermostat has to sense that the coils are cold enough. If the coils are cold enough the defrost heater will turn on. If the thermostat is defective it may not be able to sense the temperature of the coils and then won't turn on the defrost heater. If the defrost heater doesn't turn on, the frost will build up on the coils and eventually no air will be able to travel through the coils to provide cooling to the freezer or refrigerator. The defrost thermostat can be checked for continuity. It should have continuity when it reaches the low temperature of its operating range.