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June 18, 2024

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    Do you see an ‘E4’ error code on your portable or mini-split air conditioner? If your AC is displaying this code, don’t worry — usually, it’s a simple issue that you can fix yourself with a little guidance.

    In this guide, we will tell you how to troubleshoot an E4 error code and answer questions like:

    • What should you do if your air conditioner displays an error code?
    • Is it dangerous to use your air conditioning if it shows an error code?
    • Do you need to maintain your portable air conditioner or mini-split?
    • How can you properly maintain your air conditioner to avoid malfunctions?

    AC error codes are concerning, but most are easy to address with the tips below. So, let’s get into it.

    What Is An E4 Error Code?

    Technically, the E4 error is not an error at all. It actually tells you your unit is going into defrost mode. That does, however, mean that something has caused your unit to get too cold. A broken temperature sensor can also cause your AC to enter defrost mode. 

    How Often Should E4 Come On?

    Ideally, the E4 code should never appear during the normal operation of your air conditioner. That said, it may come on during extremely hot weather. If the code is appearing frequently, it usually means your AC has an ongoing issue with the outdoor temperature sensor, wiring, or refrigerant levels. Continuing to run the AC with a persistent E4 code can lead to further damage and reduced efficiency.

    Can I Stop the E4 Code?

    In most cases, yes — you can stop the error code E4 by addressing the underlying issue causing it. The E4 code typically means there’s a problem with the outdoor temperature sensor or wiring. Inspect the sensor and wiring for damage, clean any debris or corrosion, and make sure all connections are secure. If none of these work, you should call an HVAC professional for help.

    What Causes An AC To Go Into Defrost Mode?

    There are many reasons your air conditioning unit may go into defrost mode. Here are the most common causes. 

    • Low freon from a leak in the condenser coil
    • A broken heat pump
    • High pressure or low pressure 
    • It is too cold to run your AC
    • Low airflow from a clogged air filter
    • There is a broken outdoor ambient temperature sensor or indoor temperature sensor

    You would think all manufacturers would use the same codes to make it easier for repair contractors and consumers, but that is not the case. So, the above are troubleshooting tips you can use on any unit. You can also find a qualified HVAC technician to solve the problem for you.

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    Do Air Conditioner Error Codes Differ By Manufacturer Or Type?

    However, for the most part, the E4 error code means that the unit is entering defrost mode. You will hear a difference in the fan speed when your unit changes.

    When the fan motor slows, it sounds like the unit performs as an air purifier or dehumidifier. It basically just passes air over the unit without cooling it. 

    What Do Other Error Codes Mean? 

    It helps to have a reference for some of the most common error codes. So, here is a list of some that you may encounter. Print it out or bookmark this page so you do not have to search Google the next time you have a question about AC error codes. 

    F1, F2, And F3 Error Codes

    If you see any number proceeded by an ‘F,’ it is not an error code. It is simply telling you that the unit is in fan mode. The number following tells you what speed it is on.

    E Error Codes 

    Each E error code means something different. Some signify an issue with a specific component, while others tell you that the unit changed modes. 

    E1 Error Code – There is a room temperature malfunction.

    E2 Error Code – A short in the indoor pipe sensor

    E3 Error Code – An indoor fan speed problem likely attributed to a malfunctioning indoor circuit board or indoor fan motor. 

    E5 Error Code – The water collection plate is full

    E6 Error Code – A disconnect between the indoor and outdoor units possibly caused by low voltage or an open circuit. 

    E7 Error Code – The indoor and outdoor units are not working in sync. 

    E8 Error Code – Occurs sometimes in high heat or humidity. 

    E9 Error Code – A loose connection on the outside unit. 

    Keep in mind that manufacturers use different codes, and there are error codes for discharge temperature, room-temperature sensor, inverter, PCB, and other malfunctions. These codes may not indicate your specific issue. 

    It is always best to check your manual, but these are a good place to start if you do not have access to it. 

    For more information on error codes and how to resolve them, check out this video:

    A Final Thought On Now To Fix An E4 Error Code On Your Air Conditioner

    It does not matter if you are operating a portable air conditioner, mini-split, or central HVAC. Your system is complex. Many components depend on each other. 

    If one is not working properly, the unit can quickly freeze. Older systems that lack current technology could freeze over and cause a lot of damage.

    Ice can form on your indoor or outdoor unit, on the AC lines, and in the ducts. The E4 error code does not signify what is causing the unit to freeze or get too cold to operate without causing damage. 

    Air conditioners usually break on the hottest days because they have to work hardest to maintain a comfortable ambient temperature. Do not get caught off guard on a day when you need your AC the most. Choose one of our top recommended HVAC companies to help you out.


    Frequently Asked Questions

    How do I locate the outdoor temperature sensor on my AC unit?

    The outdoor temperature sensor is typically located near the outdoor coil on the AC unit. Look in your owner’s manual for the exact location of your model.


    What should I do if the outdoor sensor or wiring appears damaged?

    If you notice any visible damage to the sensor or wiring, I recommend hiring an HVAC contractor for repairs rather than attempting it yourself to avoid further issues.


    Can a dirty outdoor unit cause the E4 code?

    Yes, a buildup of debris, leaves, or dirt on the outdoor unit can cause inaccurate temperature readings and trigger the E4 code.


    Article Update Log
    6/18/2024
    Reviewed for accuracy, cost data, industry best practices, and expert advice by Jonathon Jachura.
    Editorial Contributors
    avatar for Alexis Bennett

    Alexis Bennett

    Contributor

    Alexis is a freelance writer with nearly a decade of experience covering the home services industry. She’s built considerable expertise in roofing, plumbing, and HVAC, as well as general construction and real estate matters. In her free time, Alexis enjoys coaching women’s golf. She lives in the Triad area of North Carolina.

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    Jonathon Jachura

    Contributor

    Jonathon Jachura is a two-time homeowner with hands-on experience with HVAC, gutters, plumbing, lawn care, pest control, and other aspects of owning a home. He is passionate about home maintenance and finding the best services. His main goal is to educate others with crisp, concise descriptions that any homeowner can use. Jon uses his strong technical background to create engaging, easy-to-read, and informative guides. He does most of his home and lawn projects himself but hires professional companies for the “big things.” He knows what goes into finding the best service providers and contractors. Jon studied mechanical engineering at Purdue University in Indiana and worked in the HVAC industry for 12 years. Between his various home improvement projects, he enjoys the outdoors, a good cup of coffee, and spending time with his family.

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