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Back to all UHMC100CCV4 error codes

Trane UHMC100CCV4 3 Flashes troubleshooting

Draft pressure error. 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

3 Flashes: Draft pressure error

The Trane 18-CD29D1-14-EN integrated furnace control flash-code table identifies 3 flashes as a draft pressure error with possible venting, pressure switch, or inducer problems.

System area
Draft pressure circuit
Service level
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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.

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3 Flashes questions

What does 3 Flashes mean on a Trane UHMC100CCV4?

The Trane 18-CD29D1-14-EN integrated furnace control flash-code table identifies 3 flashes as a draft pressure error with possible venting, pressure switch, or inducer problems.

What Trane message is associated with 3 Flashes?

The Trane source used for this page associates 3 Flashes with "Draft pressure error". Match the visible display text, LED pattern, or alert wording to the exact code whenever possible.

What system area does 3 Flashes point to?

This code is grouped under draft pressure circuit in the source-backed Trane troubleshooting data.

Which Trane documentation supports this 3 Flashes page?

Source-backed Trane 18-CD29D1-14-EN integrated furnace control flash-code table for XV80-style gas furnaces.

Is 3 Flashes an LED or flash-pattern code?

Yes. The Trane source row for this item is based on a displayed LED or flash pattern. Count the pattern exactly and compare it with the documented 3 Flashes entry before interpreting the fault.

Is 3 Flashes related to a pressure safety condition?

The Trane source row places this code in a pressure-related system area: Draft pressure circuit. Do not treat a pressure-safety code as a thermostat-only issue.

Is 3 Flashes related to combustion or furnace safety controls?

The Trane source row places this code in a combustion, ignition, limit, flame, or pressure-switch safety context. These codes should be interpreted from the exact equipment board and documented flash pattern.

Does 3 Flashes involve a control, board, drive, or module?

The Trane source row points to draft pressure circuit. Record the exact code and visible alert text before any reset so the control history is not lost.

What information should be captured for 3 Flashes 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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