How to Clear Carrier Furnace Fault Codes: A Comprehensive Guide

Carrier, a renowned HVAC manufacturer, utilizes a unique error code system to communicate issues with their furnaces. Understanding and clearing these fault codes is crucial for maintaining the optimal performance and efficiency of your Carrier heating system. This comprehensive guide will walk you through the process of identifying and resolving common Carrier furnace error codes, providing you with the technical expertise and hands-on instructions to tackle these problems effectively.

Understanding Carrier Furnace Error Codes

Carrier furnaces communicate error codes through a series of LED flashes. The number and pattern of these flashes correspond to specific issues, allowing you to pinpoint the problem and take the necessary steps to resolve it. Let’s dive into the most common Carrier furnace error codes and their solutions:

1. Continuous On

Meaning: The control has 24VAC power.
Solution: This is a normal operating condition, and no action is required.

2. Rapid Flashing

Meaning: Line voltage (115VAC) polarity is reversed. If the unit is twinned, refer to the twinning kit instructions.
Solution: Check the wiring for proper polarity and correct any issues. If the unit is twinned, follow the twinning kit instructions to ensure proper voltage and wiring configuration.

3. 1-1 (No Previous Code)

Meaning: Stored status codes are erased when power (115VAC or 24VAC) to the control is interrupted or 48 hours after each fault is cleared.
Solution: This is a normal operating condition, and no action is required.

4. 1-2 (Blower On After Power Up)

Meaning: The blower runs for 90 seconds if the unit is powered up during a call for heat.
Solution: This is a normal operating condition, and no action is required.

5. 1-3 (Limit or Flame Roll-Out Switch Lockout)

Meaning: The control will auto-reset after 3 hours.
Solution: Reset the switch or replace the fuse link if necessary.

6. 1-4 (Ignition Lockout)

Meaning: The control will auto-reset after 3 hours.
Solution: No action is required, as the control will automatically reset after the specified time.

7. 2-1 (Gas Heating Lockout)

Meaning: The control won’t auto-reset.
Solution: Check for a poorly wired gas valve or a defective control, and make the necessary repairs or replacements.

8. 2-2 (Abnormal Flame-Proving Signal)

Meaning: The flame is proved while the gas valve is de-energized.
Solution: Inspect the gas valve for leaks or a stuck-open condition, and replace the valve if necessary.

9. 2-3 (The Pressure Switch Didn’t Open)

Meaning: There is an obstruction in the pressure tubing or a pressure switch that is stuck.
Solution: Check the pressure tubing for any blockages and ensure the pressure switch is functioning correctly. Clean or replace the pressure switch as needed.

10. 2-4 (The Secondary Voltage Fuse is Open)

Meaning: There is a short circuit in the secondary voltage wiring.
Solution: Inspect the secondary voltage wiring for any short circuits and repair or replace the wiring as necessary.

11. 3-1 (Pressure, Draft Safeguard, Aux-Limit Switch Didn’t Close)

Meaning: There could be various issues, such as low inducer voltage, improper vent sizing, defective inducer motor, defective blower motor or capacitor, defective pressure switch, restricted vent, excessive wind, inadequate combustion air supply, or obstructed pressure tubing.
Solution: Thoroughly inspect the system components, including the inducer, blower, pressure switch, and vent system, to identify and resolve the underlying issue.

12. 3-3 (Limit or Flame Roll-Out Switch is Open)

Meaning: There could be issues with the blower motor, capacitor, dirty filter, restricted duct system, loose blower wheel, faulty switch or connections, or inadequate combustion air supply.
Solution: Examine the blower components, air filters, duct system, and combustion air supply, and make any necessary repairs or replacements.

13. 3-4 (Ignition Proving Failure)

Meaning: There could be various issues, such as build-up on the flame sensor, improper microamp distribution to the flame sensor, defective gas valve or turned-off gas valve, faulty hot surface ignitor, low inlet gas pressure, a shut-off manual valve, poor control ground continuity, low flame carryover or rough ignition, or an ungrounded flame sensor.
Solution: Thoroughly inspect the flame sensor, gas valve, ignitor, gas supply, and control ground to identify and resolve the root cause of the ignition proving failure.

Clearing Carrier Furnace Fault Codes

how to clear Carrier fault codes

To clear the fault codes on your Carrier furnace, follow these steps:

  1. Reset the Unit: Begin by resetting the unit. This can typically be done by turning off the power to the furnace, waiting for a few minutes, and then turning the power back on.
  2. Observe the LED Flashes: After resetting the unit, observe the LED flashes to identify the specific error code. Refer to the code descriptions above to understand the meaning and potential solutions.
  3. Diagnose and Resolve the Issue: Based on the error code, diagnose and resolve the underlying issue. This may involve checking wiring, replacing components, or addressing any other problems identified in the code descriptions.
  4. Verify the Fault is Cleared: Once you have taken the necessary actions to resolve the issue, verify that the fault code has been cleared. The LED should no longer be flashing the error code, indicating that the problem has been successfully addressed.

If the fault code persists or you are not comfortable performing the troubleshooting and repair steps yourself, it is recommended to contact a licensed and insured local HVAC technician. They have the expertise and tools to diagnose and fix the problem quickly and safely.

Remember, safety should always be the top priority when working with HVAC systems. If you are unsure about any aspect of the process or feel uncomfortable performing the necessary tasks, it is best to seek professional assistance.


Clearing Carrier furnace fault codes requires a thorough understanding of the error code system and the ability to diagnose and resolve the underlying issues. By following the step-by-step instructions and technical details provided in this comprehensive guide, you can effectively troubleshoot and clear common Carrier furnace error codes, ensuring the optimal performance and efficiency of your heating system.

Remember, if you encounter any difficulties or feel unsure about the process, it is always better to err on the side of caution and consult a licensed HVAC technician. They have the expertise and tools to handle these issues safely and efficiently.

Happy troubleshooting and stay warm!