Carrier HVAC Error Code 31: How to Fix It

Q: What does Carrier error code 31 mean?

Error code 31 means the low pressure switch has detected abnormally low refrigerant pressure. This usually indicates a refrigerant leak, a faulty switch, or a restriction in the system (like a frozen coil or dirty filter).

Q: Can I reset Carrier error code 31 myself?

Yes, you can try resetting the system by turning off the thermostat and power to the unit for 30 seconds, then turning it back on. However, if the underlying issue (e.g., leak or switch failure) is not fixed, the error will return.

Q: How much does it cost to fix error code 31 on a Carrier HVAC?

Costs vary: replacing a pressure switch may cost $100–$250 including labor. Fixing a refrigerant leak ranges from $200 to $1,000+, depending on leak location and refrigerant type. Always get a quote from a licensed technician.

Q: Will a dirty air filter cause Carrier error 31?

Yes, a severely dirty air filter can restrict airflow, causing the evaporator coil to get too cold and trigger the low pressure switch. Replacing the filter often resolves the issue if that’s the sole cause.

Q: Should I turn off my Carrier AC if I see error 31?

Yes, turn off the system immediately to prevent compressor damage. Running the unit with low refrigerant can overheat the compressor, leading to costly repairs.

Abstract

Carrier HVAC error code 31 indicates a low pressure switch fault, meaning the system has detected unusually low refrigerant pressure. This can be caused by a refrigerant leak, a faulty pressure switch, or airflow issues like a dirty filter or frozen coil. Follow the steps below to diagnose and resolve the issue safely.