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Troubleshooting code

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Trane 4TWV0X24A1 Alert 181.02 troubleshooting

Compressor phase loss. Use this page to document the issue and prepare for service. GreenFlow should handle diagnosis for electrical, refrigerant, lockout, or recurring conditions.

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What the code means

Alert 181.02: Compressor phase loss

The Trane variable-speed alert table identifies PHS LOSS CO when compressor cable or motor winding phase loss is detected.

System area
Compressor motor circuit
Service level
Call GreenFlow

Safe checks before calling

  • Confirm the thermostat is on, set correctly, and calling for heating or cooling.
  • Check the air filter and visible return-air path for obvious airflow restrictions.
  • Look around the outdoor unit for leaves, snow, ice, or other visible obstructions without opening the cabinet.
  • Take photos of the thermostat, outdoor unit, nameplate, and any visible flash pattern before scheduling service.

When to stop and call GreenFlow

Call GreenFlow if the code repeats, the system is locked out, heating or cooling is not restored, there is ice buildup, electrical odor, unusual noise, or any issue involving pressure switches, sensors, wiring, refrigerant, reversing-valve operation, or warranty coverage.

Share the visible code, model and serial number if available, photos, current symptoms, and whether the issue affects heating, cooling, or both.

Alert 181.02 questions

What does Alert 181.02 mean on a Trane 4TWV0X24A1?

The Trane variable-speed alert table identifies PHS LOSS CO when compressor cable or motor winding phase loss is detected.

What Trane message is associated with Alert 181.02?

The Trane source used for this page associates Alert 181.02 with "Compressor phase loss". Match the visible display text, LED pattern, or alert wording to the exact code whenever possible.

What system area does Alert 181.02 point to?

This code is grouped under compressor motor circuit in the source-backed Trane troubleshooting data.

Which Trane documentation supports this Alert 181.02 page?

Source-backed Trane 4T-V0-SF-1Q-EN Service Facts variable-speed alert-code table for 4TWV0/4TTV0 outdoor units.

What information should be captured for Alert 181.02 before clearing alerts?

Capture the exact code, any displayed alert text, the model and serial number, thermostat or control status, operating mode, symptoms, and photos of the display or LED pattern before the alert history is cleared.

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