Sub-Zero Refrigerator Error Code COLD: Compressor Stall... | appliancefaults.com

Technical Background:

The Sub-Zero's main control unit (MCU) monitors the compressor's operation via current sensors and temperature sensors. The 'COLD' error typically indicates that the MCU has detected repeated start failures or a stall condition in the compressor. The MCU sends a 120V AC signal to the compressor relay, energizing the compressor. Feedback from the current sensor allows the MCU to verify that the compressor is running properly. A stalled compressor results in an overcurrent or no current condition, triggering the COLD error.

Symptoms:

The homeowner reports that the refrigerator is not cooling and the 'COLD' error code is displayed on the control panel. They may also hear clicking sounds coming from the compressor area, indicating it's trying to start but failing. Food inside the refrigerator is warming up.

Possible Causes:

Failed start relay or overload.
Faulty compressor motor windings.
Low refrigerant charge.
Blocked or restricted refrigerant flow.
Defective main control board (MCU).
High head pressure.

Solution:

1

Unplug the Sub-Zero refrigerator from the 120V AC power outlet.
2

Locate the compressor and inspect the start relay and overload. Use a multimeter to test for continuity. Replace if necessary.
3

Check the compressor windings with a multimeter. A shorted or open winding indicates a faulty compressor.
4

Access the service port and check the refrigerant pressures. Low pressure suggests a leak.
5

Inspect the condenser coil for blockage. Clean if needed.
6

Access the main control board and check for any visible damage or burned components. Measure the voltage output to the compressor, typically 120V AC when calling for cooling.
7

If pressures are normal and the compressor is not starting, suspect a locked rotor or defective compressor and consider replacement.

Safety Warning:

Always disconnect power to the appliance before performing any repairs. Use proper Lock-Out/Tag-Out (LOTO) procedures to prevent accidental energization. Refrigeration systems operate at high pressures and contain refrigerants that can be harmful. Wear appropriate personal protective equipment.

Prevention:

Clean the condenser coils every 6 months to ensure proper airflow and prevent overheating. Avoid overloading the refrigerator with food, which can strain the cooling system. Ensure proper door seals to prevent air leaks and reduce compressor workload.

Expert Tip:

Sub-Zero units often have a service mode. To enter it, simultaneously press and hold the 'Warmer' and 'Freezer' buttons for 5 seconds. This allows you to run diagnostics and force cycles for testing.

Frequently Asked Questions

•What are the typical resistance values I should see on the compressor windings?

The resistance values depend on the compressor model. Typically, the common to start (CS) winding will have the highest resistance, followed by common to run (CR), and then run to start (RS). A shorted winding will show very low resistance, and an open winding will show infinite resistance.

•Where can I find the service port to check the refrigerant pressures?

The service ports are usually located near the compressor. Older models might have Schrader valves, while newer models may have piercing valves. You will need a manifold gauge set to properly measure the pressures.

•Is it possible to replace just the start relay and overload, or does the entire compressor need to be replaced if those components are faulty?

You can often replace the start relay and overload separately. However, if they have failed repeatedly, it may indicate an underlying issue with the compressor itself, in which case compressor replacement might be necessary.

Sub-Zero Refrigerator Error Code COLD: Compressor Stall Troubleshooting

Technical Background:

Symptoms:

Possible Causes:

Solution:

Safety Warning:

Prevention:

Expert Tip:

Frequently Asked Questions

•What are the typical resistance values I should see on the compressor windings?

•Where can I find the service port to check the refrigerant pressures?

•Is it possible to replace just the start relay and overload, or does the entire compressor need to be replaced if those components are faulty?

Related questions

Technical Background:

Symptoms:

Possible Causes:

Solution:

Safety Warning:

Prevention:

Expert Tip: