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E3

E3 — Indoor fan speed error (MMDB Indoor Units)

Lennox · Air Conditioning

What does E3 mean?

For MMDB indoor units: This error indicates an issue with the indoor fan's speed regulation. The fan might be operating at an incorrect speed or not at all.

Common Causes

  • Indoor fan motor malfunction
  • Problem with the fan speed control circuit
  • Obstruction preventing fan rotation

Repair Steps & Checklist

Click steps to track your progress.

  1. 1

    Check that the indoor unit's air intake and outlet vents are clear of obstructions.

  2. 2

    Listen to confirm if the indoor fan is running when the unit is powered on.

  3. 3

    Verify there are no physical obstructions preventing the fan from spinning.

  4. 4

    Contact a technician if the fan motor or its control board appears to be faulty.

Browse all codes in this manual (57)
Verified technical data. Last updated: April 2026

Related Faults

E0E0 — Indoor unit EEPROM error (MMDB Indoor Units)E1E1 — Communication error between indoor and outdoor units (MMDB Indoor Units)E4E4 — Indoor return air temperature sensor error
Source: Lennox Air Conditioning
Open Manual (Page 6)Search more codes in this manual