Carrier Furnace Yellow Light Codes.

Carrier Furnace Yellow Light Codes Guide.

Carrier Furnace Yellow Light Codes can be stressing when you first encounter them.When you notice that the light on your Carrier furnace is flashing yellow, it’s essentially the furnace’s way of communicating with you, albeit in a somewhat cryptic language.

This yellow light, often referred to as the “Carrier furnace yellow light code,” serves as a diagnostic tool, indicating that your furnace has encountered an issue.

Deciphering these codes can be a bit perplexing, but understanding the common meanings behind them will help you troubleshoot effectively.

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What does 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 Carrier furnace light codes below can make for faster troubleshooting when asking, “What do Carrier furnace yellow light codes mean?”

Yellow Light.

If you find yourself pondering the significance of the yellow light on your Carrier furnace, it serves as a clear indicator that your furnace is currently locked into high-fire mode.

This high-fire mode is typically intended to function briefly, expending more energy to rapidly warm an exceptionally cold home.

However, if you observe that the yellow light persists, it may suggest a protracted high-fire mode, potentially resulting from a malfunctioning gas valve solenoid within the furnace system.

How To Fix.

  • The gas valve solenoid is responsible for responding to electrical signals from the thermostat to control the flow of gas.
  • It modulates its opening to achieve low-fire mode or high-fire mode, depending on the heating requirements.
  • However, if the gas valve solenoid remains stuck in high-fire mode, it cannot be rectified through repair.
  • The only solution is to replace the malfunctioning gas valve solenoid, ensuring proper furnace functionality.

Solid Orange Light.

When you encounter a solid orange light on your Carrier furnace, it serves as a vital message within the Carrier furnace yellow light code system.

This particular signal suggests that there might be a buildup of dirt on the furnace burners, which can potentially disrupt the gas supply and, in turn, hinder the efficient production of heat.

Significance of the Carrier Furnace Yellow Light Code: The Carrier furnace yellow light code is like a language used by your furnace to communicate issues. In this context, the solid orange light is its way of saying, “Pay attention; something’s not right.”

Dirt Buildup on Furnace Burners: The culprit behind the solid orange light is often dirt and debris accumulating on the burners of your furnace. Over time, dust, soot, and other particles can accumulate on the burners, affecting their performance.

Impact on Gas Supply and Heat Production: When these burners become caked with dirt, it can impede the proper flow of gas, causing irregular combustion and reduced heat production. In some cases, it might even lead to issues like delayed ignition or erratic flames.

Importance of Maintenance: Regular maintenance is crucial to prevent this problem. Keeping your furnace clean and having it serviced by a professional at recommended intervals can help prevent dirt buildup and ensure the smooth operation of your Carrier furnace.

Also read>>>Carrier Furnace Not Turning On.

How To Fix.

  • The solid orange light on your Carrier furnace indicates an imbalance in the oxygen-to-gas ratio.
  • This imbalance may result from gas flow issues, leading to potential safety concerns.
  • In cases of gas flow problems or incorrect ratios, it is highly advisable to contact a professional furnace technician.
  • These experts can conduct a safe and thorough assessment of the problem, ensuring that your furnace operates reliably and securely.

Carrier Furnace Code 33.

When your Carrier furnace prompts a reset, it’s essential to understand that several factors could trigger this situation.

One of the prevalent causes, often associated with the Carrier furnace yellow light code, is Code 33. This code serves as a clear indicator that the flame rollout switch has been activated, and it has flipped to a position that necessitates a furnace shutdown.

This safety feature is designed to protect your furnace from overheating and potential damage.

Resetting the Furnace: When your Carrier furnace requires a reset, it signifies that the system has encountered an issue that needs your attention. Understanding the nature of this problem is key to resolving it effectively.

Code 33: The presence of Code 33 in the Carrier furnace yellow light code is the most common reason for a reset request. This specific code points to the flame rollout switch’s activation.

Flame Rollout Switch: The flame rollout switch is a crucial safety component within your furnace. When it detects abnormal conditions, such as flames extending outside the designated area, it triggers a flip to shut down the furnace. This action is essential to prevent overheating and potential hazards.

Accompanying Yellow Light: It’s worth noting that when Code 33 is in effect, the Carrier furnace yellow light often accompanies it. This yellow light serves as a visual signal that there is an issue requiring your attention.

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How To Fix.

  • When dealing with Code 33 and the accompanying yellow light on your Carrier furnace, prioritizing safety is paramount.
  • Start by conducting a thorough examination to identify potential issues, such as blockages or obstructions that could trigger flame rollout.
  • Using the services of a certified HVAC technician is highly advisable to ensure a comprehensive assessment of the situation.
  • A professional technician can make the required repairs and adjustments to guarantee the secure and optimal functioning of your Carrier furnace.

Carrier Furnace Code 31

Carrier furnace code 31 is a valuable signal that your furnace employs within the Carrier furnace yellow light code system to convey a specific issue.

In this case, Code 31 signifies a potential problem with the high-pressure switch, a critical component responsible for monitoring the air pressure inside the furnace.

When this switch activates and flips, it indicates that the pressure has exceeded safe levels.

Code 31: Code 31 is a particular message that points to a high-pressure switch problem. This switch plays a vital role in ensuring the safe operation of the furnace.

High-Pressure Switch: The high-pressure switch is designed to detect and respond to excessive air pressure within the furnace.

When the pressure becomes too high, it activates the switch to prevent potential damage and hazards.

Causes of Air Pressure Issues: Air pressure problems that trigger Code 31 can result from a couple of common factors.

One of the primary causes is the accumulation of dirt and debris on the furnace’s condenser coils. This buildup restricts airflow, causing pressure to rise. Another potential reason is a malfunctioning high-pressure switch itself.

Also read>>>Furnace leaking water.

How To Fix.

  • Begin by powering off the furnace to ensure safety during the inspection and cleaning process.
  • Examine both the inner and outer condenser coils for the presence of dust and debris.
  • If you find any accumulation, delicately clean the coils using a soft cloth to restore optimal airflow and pressure.
  • After cleaning, restart the furnace to see if the Carrier furnace code 31 has been resolved.
  • If the problem persists even after cleaning and restarting, it’s advisable to consider that the high-pressure switch may be defective and necessitates replacement. In this case, seeking professional assistance is recommended to ensure proper diagnosis and replacement.

Carrier Furnace Code 13.

When you come across the Carrier furnace yellow light code indicating a “limit switch lockout,” it’s crucial to comprehend the nature of this message.

Code 13 is a clear signal that the limit switch, a pivotal safety component in your furnace, has engaged due to an issue during the ignition process.

Interpreting Carrier Furnace Yellow Light Code: The Carrier furnace yellow light code system is like a language used by your furnace to communicate various issues. Code 13, in particular, tells you that there’s a limit switch lockout situation that needs attention.

Limit Switch Lockout: The limit switch serves as a safety feature within your furnace, and it comes into play when there’s a malfunction during the burner ignition process. Its primary role is to monitor the ignition sequence and ensure that the burners light up as intended.

Reasons for Activation: In the event that the burners fail to ignite after three consecutive attempts, the limit switch detects this issue and flips to its lockout position. This action is essential to prevent any further attempts at igniting the burners, which could potentially lead to hazardous situations.

How To Fix

  • When faced with Code 13 and the concurrent limit switch lockout, immediate action is essential.
  • Commence the resolution process by inspecting the furnace’s burners for any hindrances or potential issues that might be impeding the ignition.
  • If obstructions or problems are detected, proceed to clean or repair the burners as required.
  • In cases where the problem persists despite initial efforts, it is highly recommended to engage the expertise of a professional HVAC technician.
  • A qualified technician can conduct a thorough examination of the furnace, troubleshoot the issue comprehensively, and ensure the furnace operates safely and efficiently.

Additional Causes of a Carrier Furnace Blinking Yellow Light.

1.Low-pressure switch fault.

  • The Carrier furnace yellow light code may illuminate due to a low-pressure switch fault. This switch is a safety feature designed to monitor the gas pressure within the furnace.
  • If the switch detects that the gas pressure falls outside of the acceptable range, it triggers the yellow light as an alert.
  • A common cause of this issue is gas supply problems, such as insufficient gas pressure or a clogged gas line. It can also result from a malfunctioning low-pressure switch itself.
  • To address this, it’s important to check the gas supply, ensure proper pressure, and inspect the low-pressure switch. Professional assistance may be required to diagnose and rectify the problem effectively.

2.Blower motor malfunctions:

  • A malfunctioning blower motor can be another reason for the Carrier furnace yellow light code to illuminate. The blower motor is responsible for circulating warm air throughout your home.
  • When the blower motor encounters issues, it can disrupt the airflow and the overall heating process. This triggers the yellow light as an indication of a problem.
  • The causes of blower motor malfunctions can vary and may include problems with the motor itself, issues with the motor’s capacitor, or even problems with the thermostat.
  • Troubleshooting this issue involves inspecting the blower motor and associated components, which may require professional expertise for an accurate diagnosis and repair.

3.Reversed line voltage polarity:

  • Reversed line voltage polarity is an electrical issue that can lead to the Carrier furnace yellow light code activation. It indicates that the electrical connections in your furnace have been improperly wired, causing a polarity reversal.
  • This problem can result in incorrect voltage supply to the furnace, which can lead to erratic operation and safety concerns.
  • Correcting reversed line voltage polarity requires a careful examination of the electrical connections within the furnace, ensuring that they are wired correctly to prevent further issues and potential damage.
  • Due to the electrical nature of this problem, it is strongly recommended to have a qualified electrician or HVAC technician address the issue to prevent electrical hazards.

Also read>>>Carrier Furnace Light Blinking 3 Times.

Frequently Asked Questions (FAQs).

Why is the yellow light on my Carrier furnace flashing Code 33?

The Carrier furnace yellow light flashing Code 33 indicates a “limit switch lockout.” This occurs when there’s an issue during the burner ignition process, causing the limit switch to engage for safety.

It can be due to problems like dirty burners or ignition failures.

How can I resolve a Code 31 in my Carrier furnace, and what does it mean?

Code 31 signifies a potential issue with the high-pressure switch. It’s often associated with dirty condenser coils or a malfunctioning switch.

To resolve it, you should turn off the power, clean the coils if needed, and restart the furnace. If the problem persists, you may need professional assistance.

What should I do when I encounter Code 33 in my Carrier furnace’s yellow light code?

Code 33 indicates a limit switch lockout, usually caused by ignition issues. Start by inspecting the burners for obstructions and clean or repair them if necessary.

If the problem persists, it’s advisable to call a professional HVAC technician for a comprehensive assessment and repair.

How do I address problems associated with the low-pressure switch, blower motor malfunctions, or reversed line voltage polarity in my Carrier furnace?

  • For issues with the low-pressure switch, check the gas supply, ensure proper pressure, and inspect the switch. Professional assistance may be needed for a thorough diagnosis and repair.
  • Blower motor malfunctions require an inspection of the motor, its components, and the thermostat. Consider professional expertise for an accurate diagnosis and repair.
  • Reversed line voltage polarity is an electrical issue. Contact a qualified electrician or HVAC technician to examine and correct the wiring connections in your furnace to prevent electrical hazards.

Also read>>>Furnace Gas Valve Not Opening.


Understanding the Carrier furnace yellow light code is essential for effectively diagnosing and addressing potential issues with your furnace.

Whether it’s a limit switch lockout (Code 33), problems with the high-pressure switch, blower motor malfunctions, or reversed line voltage polarity, these codes serve as critical communication tools for your furnace’s health.

Regular maintenance and prompt action, guided by these codes, are key to ensuring the safety and efficiency of your heating system.

If in doubt or if issues persist, seeking professional assistance is a prudent step to ensure that your Carrier furnace operates reliably, keeping your home warm and comfortable.