What It Means
- Emergency alarm system on (Emergency Stop)
Lennox Air handler
Lennox Error Code 665
Air handler: Air handler (indoor)
Causes & actions from Lennox
How it shows
- Wired controller display: 665
This manual entry does not list further causes or actions.
Applicable models & manual sources
- MMD***M6-1P
Emergency alarm system on (Emergency Stop)
- MMD***S6-1P
Emergency alarm system on (Emergency Stop)
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.
