What It Means
- STRIKE3 PRIMARY HEAT 1 LIMIT OPEN
Lennox Unit controller
Lennox Unit controller Error Code 51
Unit controller
Causes & actions from Lennox
How it shows
- M4 alarm code: 51
Heat section 1 primary gas heat limit switch is open. Check air flow, air filter, limit switch and wiring. Number of occurrences is reached.
Applicable models & manual sources
- MODEL L - M4 UNIT CONTROLLER
STRIKE3 PRIMARY HEAT 1 LIMIT OPEN
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.
