What It Means
- Unit in configuration / test mode (not in normal mode)
Lennox Unit controller
Lennox Error Code Green Steady On
Unit controller
Causes & actions from Lennox
How it shows
- m4 heartbeat D33: Green Steady On
This manual entry does not list further causes or actions.
Applicable models & manual sources
- MODEL L - M4 UNIT CONTROLLER
Unit in configuration / test mode (not in normal mode)
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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