What It Means
- OUTSIDE AIR VELOCITY SENSOR ERROR
Lennox Unit controller
Lennox Error Code 99
Unit controller
Causes & actions from Lennox
How it shows
- M4 alarm code: 99
Check sensor and wiring. This alarm activates when the A24 sensor input signal is continuously above 25% of sensor measuring range for more than five minutes with blower stopped. The CORE Unit Controller will disable the Outdoor Air CFM control. The alarm automatically clears when the sensor reading is below 10% sensor measuring range for one minute.
Applicable models & manual sources
- MODEL L - M4 UNIT CONTROLLER
OUTSIDE AIR VELOCITY SENSOR ERROR
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.
