Sub-Zero Refrigerator Error Code 85: Power Supply... | appliancefaults.com

Technical Background:

The Sub-Zero's main control unit (MCU) constantly monitors the incoming power supply voltage. error code 85 indicates that the MCU has detected a voltage level exceeding the acceptable range (typically above 132V AC for a 120V system). This over-voltage condition can damage sensitive electronic components. The power supply board converts the incoming AC voltage to the DC voltages required by the various components.

Symptoms:

The Sub-Zero refrigerator displays error code 85 on the control panel. The unit may not be cooling properly, or it may shut down completely. There may be audible buzzing or humming noises coming from the back of the unit.

Possible Causes:

Incoming power surge from the utility company.
Faulty voltage regulator within the Sub-Zero's power supply board.
Loose or corroded wiring connections to the power supply board.
Malfunctioning surge protector (if installed).
Internal short circuit in a component drawing excessive current.
Grounding issue within the electrical circuit.

Solution:

1

Disconnect power to the Sub-Zero at the breaker panel.
2

Verify the incoming voltage at the receptacle using a digital multimeter. It should read 120V AC (or 240V AC depending on the model) +/- 10%.
3

Inspect the power supply board for any visible signs of damage, such as bulging capacitors or burned components.
4

Check the wiring connections to the power supply board for looseness or corrosion. Clean and tighten connections as needed.
5

If a surge protector is in use, test it to ensure it's functioning correctly. Replace if necessary.
6

If the voltage is consistently high and the power supply board appears faulty, replace the power supply board. Use the correct OEM replacement part for your Sub-Zero model.
7

After replacing the board, restore power and monitor the refrigerator to ensure the error code does not reappear. Monitor voltage using a multimeter for a minimum of 24 hours.

Safety Warning:

Disconnect power to the appliance at the breaker panel before performing any troubleshooting or repairs. Use proper Lock-Out/Tag-Out (LOTO) procedures to prevent accidental re-energization. High voltage is present in the power supply circuit.

Prevention:

Install a high-quality surge protector specifically designed for appliances. Periodically inspect wiring connections for tightness and corrosion. Have your home's electrical system inspected by a qualified electrician to ensure proper grounding.

Expert Tip:

Many Sub-Zero models have a service mode that allows you to view the real-time incoming voltage reading directly on the control panel. Consult your service manual for the specific sequence to enter service mode on your model. Use a 1/4-inch nut driver to remove the control panel if needed.

Frequently Asked Questions

•How do I determine if the power supply board is faulty?

Visually inspect the board for burned components or bulging capacitors. Use a multimeter to check the output voltages of the board against the specifications in the service manual. If the output voltages are incorrect or unstable, the board is likely faulty.

•What is the correct OEM replacement part number for my Sub-Zero power supply board?

The correct OEM part number depends on your specific Sub-Zero model number. You can find this information in your owner's manual or by contacting a Sub-Zero authorized service center. Be ready with your model and serial number.

•How do I test the surge protector?

Some surge protectors have a built-in test button. Press this button to see if the surge protector is functioning properly. You can also use a surge protector tester, available at most hardware stores, to verify that the surge protection circuitry is working.

Sub-Zero Refrigerator Error Code 85: Power Supply Voltage Too High Troubleshooting

Technical Background:

Symptoms:

Possible Causes:

Solution:

Safety Warning:

Prevention:

Expert Tip:

Frequently Asked Questions

•How do I determine if the power supply board is faulty?

•What is the correct OEM replacement part number for my Sub-Zero power supply board?

•How do I test the surge protector?

Related questions

Technical Background:

Symptoms:

Possible Causes:

Solution:

Safety Warning:

Prevention:

Expert Tip: