What It Means
- RETURN AIR OVER HEAT LIMIT
Lennox Unit controller
Lennox Unit controller Error Code 40
Unit controller
Causes & actions from Lennox
How it shows
- M4 alarm code: 40
Heat is above set point as defined by parameter 115.
Applicable models & manual sources
- MODEL L - M4 UNIT CONTROLLER
RETURN AIR OVER HEAT LIMIT
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.
What should you check next?
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