What It Means
- HEAT 2 CAI SWITCH S45
Lennox Unit controller
Lennox Error Code 64
Unit controller
Causes & actions from Lennox
How it shows
- M4 alarm code: 64
Flames have been detected outside the gas heater’s fire box.
Applicable models & manual sources
- MODEL L - M4 UNIT CONTROLLER
HEAT 2 CAI SWITCH S45
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?
Continue in ACLogics with guided diagnosis for your equipment and symptoms.
