Carrier Furnace Error Code 31 Flash: How to Fix It

Q: What causes Carrier furnace error code 31 flash?

Error code 31 flash is caused by insufficient airflow triggering the high-pressure switch. Common causes include dirty air filters, blocked vents, obstructed exhaust pipes, faulty blower motor, or damaged ductwork restricting air circulation.

Q: Can I reset Carrier furnace error code 31 flash myself?

You can try resetting the furnace by turning off power for 30 seconds, but this won't fix the underlying airflow problem. You must address the root cause (dirty filter, blocked vents, etc.) before the error will clear permanently.

Q: Is it safe to run my Carrier furnace with error code 31?

No, never bypass or ignore error code 31 flash. This safety feature prevents dangerous conditions like overheating or carbon monoxide buildup. The furnace will not operate until the airflow issue is resolved and the error clears.

Q: How much does it cost to fix Carrier furnace error code 31?

DIY fixes like replacing air filters ($15-30) or clearing blocked vents cost very little. Professional repairs range from $150-400 for high-pressure switch replacement to $300-800 for blower motor issues, depending on your location and furnace model.

Q: How often should I change my furnace filter to prevent error code 31?

Change standard 1-inch filters every 1-3 months, thicker pleated filters every 3-6 months, and high-efficiency filters every 6-12 months. Check monthly during heavy use seasons and replace when visibly dirty to maintain proper airflow.

Abstract

Carrier furnace error code 31 flash indicates the high-pressure switch did not close or reopened during a call for heat. This safety feature prevents your furnace from operating when there's insufficient airflow or a blocked vent, which could cause dangerous conditions.