Sub Zero refrigerators have several common issues. If your refrigerator is not cooling, there are a few things you need to check. Most new refrigerators use electronics and thermistors to regulate the temperature inside the freezer and refrigerator. On the majority of Sub Zero refrigerators there is a small control behind the dial that regulates the temperature. This control is known as a cold control. It’s what sends power to the compressor to get the freon flowing to the evaporator.
If you set the temperature using electronics on the display board, then your Sub Zero model uses a thermistor to regulate the temp. For this article I want to explain why and how a bad cold control will cause a no cool issue with the freezer or refrigerator. If you have the electronic model and need help diagnosing your refrigerator, use the Free Repair Forum for technical help.
The first thing you want to check and see in a no cool event is the compressor. Is the compressor running. Is the compressor hot/warm? If the compressor is cold to the touch, then you likely have a cold control problem. The compressor on these refrigerators are hot. Given they are sealed wither on the top or bottom of the unit a lot of heat builds up inside the cavity. If the compressor is not hot then you need to figure out if the compressor is getting power. A volt meter is needed to verify this. If no power is present at the overload relay, you need to check the cold control.
So we’ve determined that the compressor is cold and is not getting power to the overload. The next thing we need to do is to take the inside apart to gain access to the cold control. Remove the plastic light housing in the top of the unit. You may need to remove the upper most shelf to get the housing out of the refrigerator. Once out you will need to remove the screws that hold the cover over the evaporator fan motor. Once the cover is off you will notice three small screws. Once the three small screws are removed, the back panel inside the refrigerator will come out enough so the cold control can be tested.
Now we have the back panel out and have access to the cold control. The next step would be to ohm or make a continuity check of the cold control. With the volt meter set it to the continuity setting or ohm’s setting. Remove at least one wire off the cold control. That way you don’t get a false reading. With the dial on the cold control set to the middle check the two prongs on the cold control. You should hear a beep or see a ohm’s reading on the meter. If the meter reads open line or does not show continuity, then you have a faulty cold control.
As you can see the wire coming off the cold control goes down and sits against the black evaporator behind the back panel. When the freon is pumped to the evaporator it boils. When freon boils it creates frost. The heat is absorbing the heat inside the refrigerator back into the refrigeration system and dissipating it at the condenser. That’s why you always hear people say keep your condenser coils clean. The heat transfer for the refrigeration system happens their.
So now you’ve figured out why your Sub Zero refrigerator is not cooling. You next step is to check with your local appliance parts supplier and see if the have the part in stock.
If you require assistance after reading this Sub Zero Refrigerator not cooling article, please sign up at our free repair forum and a Factory trained Sub Zero repair specialist will assist you in your refrigerator troubleshooting.