4 🟡 Repair Required
Lennox Error Code 4: High Limit Switch Open
⚠️ Your Lennox HVAC system has detected a high temperature and has shut down to prevent damage. Call a professional for repair.
How to Fix Lennox Code 4
- Check if your air filter is clean. A clogged filter can restrict airflow and cause the system to overheat.
- Ensure that all vents are open and unobstructed to allow for proper airflow.
- If the issue persists, do not attempt to open the unit or perform any further troubleshooting. Call a professional HVAC technician.
What Does Lennox Error Code 4 Mean?
The Lennox 4 error, or High Limit Switch Open, indicates that your HVAC system has detected an abnormally high temperature and has shut down to prevent potential damage to the unit. This is a safety feature designed to protect your system and your home. The high limit switch is a safety device that monitors the temperature of the air leaving your furnace or air handler. If the temperature exceeds the set limit, the switch opens and shuts down the system.
Common Causes of Lennox Code 4
- A faulty high limit switch
- A problem with the temperature sensor
- Blocked or restricted airflow over the heat exchanger
- A malfunctioning inducer motor or draft inducer fan
Applicable Lennox Models
Need a Pro to Fix Lennox Code 4?
A licensed HVAC technician can diagnose and fix this issue quickly.
Find a Licensed Tech Near You →Replacement Parts for Lennox Furnace Code 4
High Limit Switch OEM: 34A2011-000
Temperature Sensor