When the light on your Carrier furnace is yellow and flashing it’s like your furnace is speaking a different language. You know it’s communicating a problem but how do you determine what do Carrier furnace yellow light codes mean? We’ll review some common meanings such as a limit switch lockout or a flipped flame roll out switch to help break the code.

Common Answers to What Do Carrier Furnace Yellow Light Codes Mean

When your Carrier furnace suffers a malfunction it uses two digit number codes to alert you. The first digit is the number of flashes by the yellow light while the second digit is the number of green light flashes. The common yellow light codes below can make for faster troubleshooting when asking, “What do Carrier furnace yellow light codes mean?”

Yellow Light

What it means: If you’re wondering, “What does the yellow light on my Carrier furnace mean?” it signifies that the furnace is stuck in high-fire mode. The high-fire mode should only operate for short periods of time to heat a very cold house faster. If the yellow light remains on this could indicate that the furnace is stuck in high fire mode due to a defective gas valve solenoid.

How to fix:  The gas valve solenoid uses an electric signal to open when the thermostat calls for heat, narrowing its opening for low-fire mode and widening for high fire mode. A gas valve solenoid stuck in high fire mode can’t be repaired and needs to be replaced.

what do carrier furnace yellow light codes mean

Photo Credit: Just Answer


What it means: A Carrier furnace calling for a reset can have multiple causes. The most common reason is Code 33, indicating that the flame roll out switch has been flipped. This switch is a safety feature that flips to shut the furnace down and prevent it from overheating. This code is often accompanied by the above yellow light.

How to fix: We recommend consulting your manual for the specific steps involved in resetting the flame roll out switch for your model furnace. If this task is outside your DIY comfort zone we recommend a professional service.

Code 31

What it means: Code 31 typically indicates a problem with the high pressure switch. This switch senses the amount of air pressure inside the furnace and will flip if the pressure is too high. Air pressure issues can occur when the furnace’s condenser coils are dirty or if the high pressure switch is faulty.

How to fix: Turn off power to the furnace. Check both the inner and outer condenser coils for dust and debris, gently cleaning with a soft cloth if needed. If the code still remains after restarting the furnace then the high pressure switch may be faulty and requires replacement.

Code 13

What it means: This code usually signifies a limit switch lockout. This switch is also a safety feature that engages when there’s a malfunction in lighting the furnace burners. If the burners fail to ignite after three attempts the switch flips and cuts off any gas flow to the burner.

How to fix: So how do you fix Error Code 13 on a Carrier furnace? While this switch can flip if an airflow vent is blocked or if the switch is faulty, it can also trip when there is a gas flow problem. As this situation can be dangerous, we recommend a professional service to assess the problem.

Blinking Light

What it means: If you’re wondering what does the blinking light on my Carrier furnace mean there could be several answers. While Codes 31, 33 & 13 are the most common, here are some additional blinking light meanings:

  • Problem A: Low pressure switch fault
  • Problem B: Blower motor malfunctions
  • Problem C: Reversed line voltage polarity

How to fix:

  • Problem A: Clean the condenser coils. If the code remains, the low pressure switch may be faulty and need replacement
  • Problem B: Check the furnace filter, replacing if dirty. If the code remains, the blower motor will need to be professionally assessed for a malfunction.
  • Problem C: this can occur when the furnace is not properly grounded to your electrical panel or when there is a control panel failure. A professional service can assess this problem.

We hope we solved the mystery of what do Carrier furnace yellow light codes mean with our guide to some common codes. If you need help breaking a code or troubleshooting a loud furnace, Dependable Heating and Air can help. Call us any time you need to fix a furnace fast!