Troubleshooting Sub-Zero Refrigerator

Troubleshooting Sub-Zero Refrigerator

Due to the danger and complexity of electronic equipment repair, the following technical tip is intended for professional reference only. Please refer to manufacturer’s recommendations as Encompass does not guarantee the accuracy, reliability or safety of this information. 

Sub-Zero is one of America’s most renowned refrigerator brands, thanks to its legendary quality and features. This post covers troubleshooting and suggested repairs for the following models:

  • Model 700TR
  • Model 736TR
  • Model 700TF(I)
  • Model 736TFI
  • Model 700TC(I)
  • Model 736TCI
  • Model 700BR
  • Model 700BF(I)
  • Model 700BC(I)

Sub-Zero refrigerators typically require minimal maintenance and operate efficiently. However, integrated units can sometimes malfunction, indicate errors or fail to perform as expected. Here are some common issues:

Refrigerator or Freezer Unit Frosted Up

After some time, the Sub-Zero refrigerator may frost up around the cooling element. This can adversely affect cooling performance and puts more pressure on the motor. It also takes up space in the appliance’s internal compartment, leaving less space for food storage.

Here’s the fix:

  1. Determine if refrigerator door accidentally left open — This can allow moisture into the appliance, which then condenses on the refrigerant at the rear of the unit where it eventually freezes.
  2. Check seals around door — If seals are damaged, moldy or missing, air can freely circulate into the unit, allowing moisture to condense and form ice deposits. You can order a replacement gasket (door seal) from Sub-Zero. Heavy use limits the life of gaskets. The brand supplies the following gasket types:
    • BI – for Classic Series door replacement
    • IT, IC – for Designer Series and Designer Wine Storage replacement
    • PRO3650 and PRO4850 – for door gasket replacement
    • Generic parts are available if you are unable to source OEM.

Refrigerator Not Operating

Occasionally, Sub-Zero refrigerators will stop working entirely. Don’t assume the unit has come to the end of its useful life. Simple fixes can often resolve the problem.

Here are steps to try:

  1. Ensure power on — If appliances are on a separate circuit, check to see if the switch has tripped in the fuse box. Also, ensure that any buttons on the unit are set to the on or “1” position.
  2. Ensure refrigerator control on — Sub-Zero refrigerators come with a thermostat that continuously senses the internal temperature of the appliance and adjusts cooling power accordingly. Sometimes, however, it fails to switch the compressor on, even when the fridge interior gets warm, making it seem as if the appliance is not operating. Try installing a new Sub-Zero thermostat. On refrigerators, the control is on the top right of the back wall.
  3. Check to ensure unit not in showroom mode — If this might be the case, contact Sub-Zero customer service for step-by-step instructions on how to convert it to normal mode.
  4. See if unit is in defrost mode — Sub-Zero refrigerators periodically shut off the cooling unit to allow for de-icing. Wait half an hour to see if the unit restarts.

Ice Maker Not Working

Check to ensure the ice maker is:

  1. Turned on at control panel.
  2. Connected to water supply and operating properly.
  3. Also check to ensure the ice container is in correct position in freezer drawer.

“SERVICE” Warning Flashing On Control Panel Display

Sub-Zero refrigerators come with sensors that alert when service is needed:

  1. When “SERVICE” flashes, it could mean the condenser needs to be cleaned. This is the part of the refrigerator that transfers heat from the refrigerant to the air. Begin by switching the unit off and then switching it back on again. If the error message persists, contact a Sub-Zero-accredited repair engineer as this is not a DIY fix.
  2. On fridge-freezer units, if the error codes “SERVICE” and “ICE” are flashing, try above method and restart the unit to see if the alerts go away. If not, contact Sub-Zero-accredited repair engineer

Refrigerator Running Warmer than Usual

Occasionally, Sub-Zero refrigerators run warmer than usual, even if cooling is at the maximum setting.

Here’s the fix:

  1. Ensure control is set properly — It may have accidentally been set too warm.
  2. Ensure condenser area clean — If it isn’t, try unplugging unit from the wall and dusting around the area. If the problem is inside the unit, contact an accredited Sub-Zero repair engineer.
  3. Excessive and/or hot contents Has a large amount of food been recently stored inside? Solids tend to retain their heat longer than gases and require more energy to cool. If the unit was just loaded with fresh shopping or hot food, the temperature will rise, making it seem as if it’s running hot. Wait awhile and then check the temperature again to see if it’s still elevated.
  4. Doors or drawers kept opened Refrigerators are powerful enough to cool interiors, but they can’t cool a home. Make sure nothing is obstructing openings and preventing closure.

Refrigerator Runs Longer than Usual

Sub-Zero refrigerators should run only when the temperature rises above the set level. The rest of the time, they rely on insulation to keep food chilled. However, sometimes the refrigerator continues running for longer periods. Here’s the fix:

  1. Consider weather — On hot days, units will run longer to maintain cooler internal temperatures.
  2. Open doors Make sure doors are always tightly closed with no obstructions.
  3. Condenser — Check to ensure condenser area is clean.

Light Bulb Out

The lightbulb could fail in either the drawer or top compartment, making it difficult to see inside. Here’s the fix:

  1. Replace top compartment light with standard 40-watt bulb – code 3030030.
  2. Replace drawer compartment light with standard 25-watt bulb – code 3030060.


Visit Fred’s Appliance Academy to learn more about the training provided in appliance repair.

Special thanks to Fred’s Appliance Academy for this helpful tip!

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