What It Means
- Heating operation blocked
Lennox Air handler
Lennox Air handler Error Code 440
Air handler: Air handler (indoor)
Causes & actions from Lennox
How it shows
- Wired controller display: 440
This manual entry does not list further causes or actions.
Applicable models & manual sources
- MMD***M6-1P
Heating operation blocked
- MMD***S6-1P
Heating operation blocked
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?
Continue in ACLogics with guided diagnosis for your equipment and symptoms.
