Lennox HVAC Error Code 106

Error code 106 on a Lennox air handler indicates a hardware problem with the air-handler control board. The board has detected an internal fault that goes beyond a simple sensor or communication issue. If the condition is temporary, the alarm clears automatically 300 seconds after the fault recovers. If the fault is persistent and prevents operation, the control board needs to be replaced.

A code 106 fault itself is not typically a immediate safety hazard, but it can prevent the air handler from operating correctly. If the system stops running during extreme temperatures, comfort and pipe-freeze risks can become concerns. It is best to address the fault promptly rather than leaving the system inactive for an extended period.

The system is designed to clear the code automatically 300 seconds after the hardware fault recovers on its own. Power-cycling the air handler may temporarily clear the fault, but if the control board has a genuine internal hardware failure, the code will return. A reset is not a fix for a persistent code 106 and should only be treated as a temporary diagnostic step.

Because code 106 points to a hardware fault inside the control board, there are very few DIY fixes available. You can check that the air handler is receiving stable power and that no circuit breakers are tripped, but diagnosing and replacing an air-handler control board requires electrical knowledge and familiarity with HVAC systems. Most homeowners will need a qualified HVAC technician to resolve a persistent code 106.

If the fault is caused by a transient power issue, there may be no parts cost at all. If the control board requires replacement, parts and labor costs typically range from a few hundred dollars to over five hundred dollars depending on the specific board model and local labor rates. Getting a quote from a certified HVAC technician before authorizing repairs is recommended.