Lennox Unit controller

Lennox Unit controller Error Code 108

Unit controller

What It Means

  • SUPPLY DUCT PRESS LIMIT EXCEEDED

Causes & actions from Lennox

How it shows
  • M4 alarm code: 108

• Check sensor and wiring. • The CORE Unit Controller will shutdown operation for Error Off time (Parameter 110) if supply air static pressure exceeds supply static shutdown setpoint for 20 seconds (default) Parameter 42. • The CORE Unit Controller will clear High Supply Static (Duct) Pressure after Error Off Time has expired and static duct pressure is below Supply Static Set Point Shutdown.

Applicable models & manual sources
Disclaimer: This information is for general reference. Code wording and instructions vary by model. Always follow the service manual for your exact unit.

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