Sub Zero refrigerators are very common in our service area. Fixing a Sub Zero yourself is fairly simple with the proper guidance. Sub Zero uses a cold control to start and stop the refrigerators compressor. When this cold control fails the compressor will not start, creating a no cool situation in the freezer or the refrigerator section of a Sub Zero refrigerator.
To diagnose this issue a volt or ohm meter will be needed, a resistance check of the cold controls terminals will need to be made determining if the control has failed. There are two separate cold controls since two compressors are used on Sub Zero refrigerators. In this article we are going to access and test the refrigerator side of the built in.
To gain access to the cold control on bottom mount refrigerators the rear panel will need to be removed in order to test and replace the component. Remove the light cover by pressing in on the cover’s front. This will release the clips that hold the light cover in place.
With the refrigerator light cover removed the evaporator cover will need to be removed next, remove each small Philip screw located on each end. When removed the fan motor cover will slide forward and off. Next remove the screws located on the top edge of the rear panel. Once removed the refrigerator’s back panel will fall forward enough to lift out of the clips that hold it on the bottom.
The cold control is mounted to the back of the rear panel. The temperature knob sits on the shaft of the cold control. Remove the temperature knob followed by the nut that holds the control to the back panel. Once off we can now test the cold control.
Remove the two wires on the control. Next set your volt meter to ohm setting (a continuity test is also acceptable). Touch both volt meter leads to the cold control leads. If the control is room temperature the meter should beep or a resistance reading on the terminals will indicate a normally operating control.
When the cold controls bulb warms up contact is made inside sending voltage to the compressor and condenser fan motor. Once the control is satisfied contact is broken and the compressor and fans shut down. If the control is satisfied and an ohm test is made resulting in no resistance or continuity this could be because the control contact is in the open position.
If no volt meter is available or you are not able to read a volt meter, bypassing the thermostat is an option. To learn how to do so you can post your question in our DIY repair forum and a certified technician will assist you with your Sub Zero or appliance repair question.