What It Means
- DAMPER STUCK OPEN
Lennox Unit controller
Lennox Error Code 139
Unit controller
Causes & actions from Lennox
How it shows
- M4 alarm code: 139
• The Damper is not closing to the target percentage. Unit may be bringing in more than anticipated outdoor air. • Inspect damper and / or actuator for blockage. alarm is raised when damper actuator feedback exceeds 2v under target for 2 minutes. • Alarm will reset automatically when damper feedback falls to 1.8v within the target voltage.
Applicable models & manual sources
- MODEL L - M4 UNIT CONTROLLER
DAMPER STUCK OPEN
MODEL L - M4 UNIT CONTROLLER, M4 Unit Controller
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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