Sub-Zero Freezer Error Code r2: Relay Fault... | appliancefaults.com

Technical Background:

The MCU (Main Control Unit) monitors the freezer relay circuit. The relay is responsible for supplying power to the freezer compressor. When the MCU detects an issue with this circuit, such as an open or shorted relay coil, or a lack of voltage to the compressor, it triggers the 'r2' error code.

Symptoms:

The US homeowner observes the Sub-Zero refrigerator displaying error code 'r2'. The freezer may not be cooling properly, or the compressor may not be running. The unit may also be cycling on and off frequently, or not at all.

Possible Causes:

Faulty freezer relay on the control board.
Wiring harness issue between the control board and the relay.
Loose connection at the relay or control board.
Failed freezer compressor overload protector.
Defective main control board (MCU).
Compressor winding fault.

Solution:

1

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

Locate the main control board (MCU), typically behind an access panel on the top or back of the unit.
3

Visually inspect the wiring harness and connections to the freezer relay on the board for damage or looseness. Secure any loose connections.
4

Using a multimeter, test the freezer relay coil for continuity. An open or shorted coil indicates a faulty relay. Replace the relay if needed. Replacement relays can often be soldered directly onto the control board.
5

If the relay tests good, use your multimeter to check the voltage (typically 120V AC) being sent to the compressor from the relay when the unit is calling for cooling. If no voltage is present, the control board is likely defective and needs replacement.
6

Examine the compressor overload protector with a multimeter. It should show continuity when tested. Replace if open circuit.
7

Reconnect power and monitor the unit for proper operation. Clear the error code by pressing and holding the reset button on the control board (if available), or by power cycling the unit.

Safety Warning:

Always disconnect power to the appliance at the breaker panel before performing any repairs. Use Lock-Out/Tag-Out (LOTO) procedures to prevent accidental re-energization. Be aware of high voltage components on the control board.

Prevention:

Regularly inspect the refrigerator's wiring harness for damage or wear. Ensure proper ventilation around the unit to prevent overheating, which can stress the control board components.

Expert Tip:

Some Sub-Zero models have a service mode that allows you to manually activate the freezer relay for testing purposes. The sequence varies by model, consult the service manual.

Frequently Asked Questions

•How do I access the main control board on my specific Sub-Zero model?

The location varies depending on the model. Consult your service manual or search online using your model number for diagrams. Generally, it's behind a top or rear access panel.

•What are the typical voltage readings I should expect on the freezer relay when the compressor is running?

You should typically see 120V AC on the output side of the relay when the compressor is energized.

•Where can I find a replacement freezer relay for my Sub-Zero refrigerator's control board?

You can purchase replacement relays from appliance parts suppliers online. Be sure to match the relay's specifications (voltage, current rating, coil resistance) to the original component.

Sub-Zero Freezer Error Code r2: Relay Fault Troubleshooting

Technical Background:

Symptoms:

Possible Causes:

Solution:

Safety Warning:

Prevention:

Expert Tip:

Frequently Asked Questions

•How do I access the main control board on my specific Sub-Zero model?

•What are the typical voltage readings I should expect on the freezer relay when the compressor is running?

•Where can I find a replacement freezer relay for my Sub-Zero refrigerator's control board?

Related questions

Technical Background:

Symptoms:

Possible Causes:

Solution:

Safety Warning:

Prevention:

Expert Tip: