Lennox Mini Split Error Codes and What They Could Mean

Understanding Mini Split Error Codes

Are you stumped by a strange code flashing on your mini-split? Navigate the maze of mini-split error codes with our concise troubleshooting guide. Find out what each code signals and the straightforward actions you can take to remedy the most common issues, such as sensor glitches or electrical misreads, without revealing the complete diagnostics—no jargon, no fluff—just clear, helpful advice to restore your system’s functionality.

Key Takeaways

  • – Mini split systems communicate issues via error codes indicating problems such as faulty wiring, sensor malfunctions, incorrect voltage readings, and PCB issues, with specific codes like E1, E5, E6, P4, and P6 representing common problems that require prompt attention.
  • – Error codes are not standardized across all mini-split models, highlighting the importance of consulting the specific model’s manual or manufacturer’s website for accurate troubleshooting and understanding the peculiarities of different mini-split systems.
  • – Regular maintenance, including biannual professional checkups and DIY inspections, is critical for mini-split systems’ optimal performance and longevity. You should seek professional help for complex repairs, especially electrical components and part replacements.

Understanding Mini Split Error Codes

Understanding Mini Split Error Codes
Understanding Mini Split Error Codes

Mini-split systems primarily communicate through error codes, which form the core of their communication system. These codes are not merely random numbers and letters but a signal from your system highlighting an issue that needs your attention. Understanding these codes empowers you to hasten repairs, saving time and avoiding unnecessary costs.

The error codes primarily result from:

  • Faulty wiring
  • Sensor malfunctions
  • Incorrect voltage readings from these sensors
  • A faulty PCB (Printed Circuit Board)

Ignoring these warnings can lead to a complete system failure. Therefore, promptly addressing and resolving these warnings is crucial before considering a mini-split replacement process.

E1 – Indoor / Outdoor Unit Communication Breakdown

Envision a scenario where your indoor and outdoor units cannot communicate with each other. Sounds problematic, right? That’s precisely what an E1 error code signifies – a breakdown in communication between the indoor and outdoor units of your mini split system. This breakdown often results from high pressure in the system or a communication malfunction between these units.

The consequences can range from inadequate heating or cooling, failure to power on or off, and even error message displays on the control panel. You can attempt to rectify this by confirming the settings to ensure all units are set for cooling mode, or by power cycling the system. If these steps prove ineffective, consider seeking help from a professional technician or consulting the manufacturer’s manual for further guidance.

E5 – Voltage Protection or Temperature Sensor Malfunction

Next in line is the E5 error code. It’s like a red flag indicating voltage protection or temperature sensor malfunction in your mini split system. If you notice fluctuating or unstable voltage levels, inaccurate temperature readings, and insufficient protection of system components from voltage fluctuations, it is likely that your system is experiencing a temperature sensor error.

Potential causes of these malfunctions include improper installation, a faulty thermostat, or a faulty temperature sensor. If these issues persist, seeking professional help is the way to go. Remember, a malfunction in a mini split system can be identified through error codes, monitoring temperature inconsistencies, testing voltage levels, and seeking advice from a professional in the field.

E6 – Indoor / Outdoor Unit Communication Hurdle

An E6 error code, like the E1 code, indicates a communication issue between your indoor and outdoor units. However, it could also signal a malfunctioning temperature sensor. This error code is usually the result of communication failure between the indoor and outdoor units, often due to problems with the communication wires or voltage issues.

Addressing an E6 error code involves a series of steps:

  1. Power cycling the system
  2. Checking wiring connections between indoor and outdoor units
  3. Ensuring condensate pumps function correctly
  4. Contacting a professional if the error persists.

To avoid the reoccurrence of this error, you can take the following steps:

  1. Regularly power cycle your system.
  2. Verify proper connection and absence of damage in control wires.
  3. Consider replacing faulty control boards.
  4. Ensure optimal communication between units by replacing any damaged wires.

By following these steps, you can prevent the error from happening again.

P4 – Compressor Drive Concern / High Temperature

The P4 error code is a signal that raises concerns about the compressor drive or high temperature issues, potentially related to discharge line temperature. A P4 error code can be triggered by a plethora of causes, including:

  • Abnormal inverter compressor drive due to a wiring mistake
  • IPM malfunction
  • Faulty outdoor fan assembly
  • Wrong voltage applied or power surge
  • Mixed up wiring
  • Discharge pipe over temperature protection
  • High, low, or imbalance voltage
  • Shorted PC and/or IPM boards
  • Problems with the compressor
  • Power supply abnormality
  • Poor condenser heat exchange
  • High pressure side issues

A high temperature can lead to the overheating of the compressor, often a result of high superheat, which may occur due to low charge or hindered migration of cool gas to the compressor. Therefore, it is essential to maintain the appropriate discharge line temperature for effective system operation.

P6 – Compressor Switch Open or Drive Board Malfunction

The final error code we will discuss, the P6 error code, signifies a compressor switch open or drive board malfunction. Typical factors leading to a P6 error code include low refrigerant pressure, open high or low-pressure switch, and a faulty indoor coil thermistor.

A compressor switch open or drive board malfunction can cause the compressor not to start or shut off prematurely, resulting in inadequate cooling or heating. If you notice a decrease in pressure on the gauges to zero, issues with high or low pressure, or a defective current sampling circuit component on the drive board, you might be facing a P6 error.

Recommended immediate actions include:

  • Verifying the refrigerant levels for adequacy and potential leaks
  • Examining and removing any obstructions from the outdoor unit
  • Performing a system reset

If these measures do not resolve the issue, it is advisable to seek assistance from a professional technician.

Consult Your Mini Split Model’s Manual

Consult Mini Split Manual
Consult Mini Split Manual

As demonstrated, comprehending your mini split system’s error codes is of great importance. However, a noteworthy point is that error codes are not standardized across all mini split models. Different manufacturers may utilize unique error codes for specific issues, underscoring the importance of referring to the manual tailored to your model.

Therefore, consulting the manual for your specific mini split model is vital for understanding error codes and troubleshooting procedures. If you don’t have a physical copy, you can usually find a digital version on the manufacturer’s website under the support or downloads section using your model number, or conduct a search engine query with the model number and the term ‘manual’.

Heat Pump Models

Heat pump models of mini splits possess unique error codes, including E1, high pressure, and serial communication error. Although some error codes may be similar or have consistent meanings, it is important to refer to the manufacturer’s documentation or reach out to customer support for precise information regarding error codes for a specific model.

The recommended troubleshooting procedures for common error codes in heat pump models include:

  1. Decoding the error codes
  2. Checking for power supply issues
  3. Inspecting the filters
  4. Checking the outdoor unit
  5. Verifying the thermostat settings

If issues persist after these steps, it is advisable to seek assistance from a professional HVAC technician.

Mini Split Air Conditioners

Similarly, mini split air conditioner models also have unique error codes and troubleshooting steps. Frequently encountered error codes in Mini Split Air Conditioners can differ based on the brand and model. Nevertheless, some common error codes comprise:

  • E1
  • E2
  • E3
  • E4
  • E5

When troubleshooting Mini Split Air Conditioner error codes, follow these steps:

  1. Confirm that both indoor and outdoor units are set to the same mode.
  2. Check the proper functioning of all fans.
  3. If encountering a specific error code, consult the manufacturer’s manual or website for relevant troubleshooting procedures.

If the problem persists, it is recommended to seek assistance from a professional HVAC technician.

Regular Maintenance and Prevention

Mini Split Professional HVAC Technician
Mini Split Professional HVAC Technician

Similar to any machine, your Lennox mini split system requires regular maintenance and attention, especially for the mini split system’s indoor components and the mini splits compressor system. Consistent maintenance and prevention can aid in averting system issues and extending the lifespan of your Lennox mini split systems. If you notice unusual odors or noises emanating from the mini split ac system, it is advisable to seek assistance from your HVAC professional.

Biannual Checkups

Biannual checkups conducted by a professional technician can be one of the most effective strategies for maintaining your mini split system in optimal condition. These checkups can assist in:

  • Identifying potential issues
  • Sustaining peak system performance
  • Enhancing the longevity of a mini split system through proper maintenance
  • Improving efficiency

A biannual mini split system maintenance involves a series of standard procedures such as inspecting the air handler, checking the discharge air temperature, cleaning the indoor coil and blower wheel, verifying refrigerant pressure, and performing a visual inspection for leaks or damage. During a semiannual inspection, various common issues can be identified, including refrigerant leaks, sensor malfunctions, drainage issues, inadequate heating or cooling, unusual noises, and indications of corrosion.

DIY Inspection

Alongside professional checkups, you can also engage in self-conducted inspections. To perform a self-conducted inspection, it is recommended to:

  1. Begin by assessing the cleanliness and presence of debris around the exterior of the unit.
  2. Ensure that the condenser mount is securely in place and that the unit is level.
  3. Inspect the indoor unit for water leaks, unusual noises, and any signs of damage to the fan, blower, and evaporator.
  4. Clean both the indoor and outdoor units.
  5. Check the refrigerant levels.

Typical indicators to be on the lookout for include inadequate airflow, refrigerant leaks, sensor issues, drainage problems, and ineffective heating or cooling. One should be vigilant for uncommon odors such as mold, mildew, or burning, which could indicate the presence of mold, animal remains, or electrical problems. Additionally, one should be cautious of high-pitched whistling, grinding, gurgling, loud noises, rattling, buzzing, foul odors, or squealing, as these may all suggest a malfunction.

Keep in mind, if you encounter any uncertainties while resolving issues during the inspection, it’s always recommended to consult a professional.

Seeking Professional Help for Mini Split Repair

Professional technician inspecting electrical components
Professional technician inspecting electrical components

Despite the benefits of understanding error codes and carrying out regular maintenance, there might be occasions where professional help becomes necessary. Professional assistance for mini split repair is crucial for the following reasons:

  • To meet warranty requirements
  • To avert potential future repairs
  • To enhance system efficiency and air quality
  • To guarantee safe unit operation
  • To contribute to carbon footprint reduction.

Moreover, professionals can mitigate risks associated with DIY repair, such as higher repair costs, potential injuries, safety hazards, risk of home damage, and system malfunction.

Electrical Component Troubleshooting

Troubleshooting electrical components forms a vital aspect of prompt mini split repair, necessitating professional expertise. When troubleshooting electrical components in mini split systems, it is essential to adhere to safety precautions such as:

  • Avoiding water
  • Ensuring the system is powered off and disconnected from the power source
  • Using insulated gloves and safety glasses
  • Utilizing proper connecting wires

Essential tools for electrical troubleshooting in mini split systems consist of wire strippers, screwdrivers, pliers, screw-on wire connectors, and a non-contact voltage tester. To diagnose electrical problems in mini split systems, it is recommended to check the power supply, inspect the wiring, test the voltage, examine the control board, and evaluate the capacitors.

Indications of electrical malfunction in mini split systems may include:

  • Low output
  • Leaking water
  • Communication issues
  • Damaged boards or compressors
  • Refrigerant leaks
  • Sensor problems
  • Inadequate heating or cooling
  • Unusual odors such as a burning smell.

Replacing Faulty Parts

The task of replacing faulty parts in mini split systems is ideally delegated to professionals. Indications that components of your mini split system may require replacement include:

  • Signs of aging and wear
  • Mechanical malfunction
  • Insufficient heating or cooling
  • Refrigerant leaks
  • Unusual odors

When one part requires replacement, it is typically advisable to consider replacing other aged or worn components as well.

Typical faulty components in a mini split system encompass thermostat settings, dirty air filters, refrigerant leaks, blocked coils or fins, and improper installation. Detection of issues with these elements may indicate a requirement for fast mini split repair. The process of replacing faulty parts in a mini split by a professional includes inspecting the system, identifying the defective component, removing it, and installing a new one. This ensures that the repair is performed accurately and safely, underscoring the importance of seeking assistance from a heating and cooling professional.


In conclusion, understanding error codes, conducting regular maintenance, and seeking professional help when necessary can significantly improve the performance and lifespan of your mini split system. By empowering yourself with this knowledge, you not only ensure a comfortable and healthy living environment but also avoid unnecessary costs and hassles. Remember, your mini split system is a long-term investment that deserves your attention and care. So, let’s start speaking the language of our mini split systems, shall we?

Frequently Asked Questions

How do you reset a mini-split?

To reset a mini-split, simply turn off the unit, unplug it, wait for 15 minutes, then plug it back in and turn it on. This can often resolve minor issues.

What do the symbols on a mini-split mean?

The symbols on a mini-split remote indicate the mode of operation: a snowflake for Cool Mode, a sun for Heat Mode, a fan for Fan Mode, and a raindrop for Dry/Dehumidification. These symbols are displayed at the top of the remote display.

How do you troubleshoot a mini-split?

To troubleshoot a mini-split system, you can start by examining the outdoor unit, checking the power supply, cleaning the drain line, and addressing issues such as dirty vents or filters, refrigerant leaks, and evaporator coils. Keeping an eye on these components can help identify and resolve potential problems before they escalate.

What is the E6 code on a mini-split?

If you’re seeing an E6 error code on your mini-split, it indicates a communication problem between the indoor and outdoor units or a malfunction in one of the temperature sensors, similar to an E1 code. Consider checking these components for issues.

What is the significance of understanding mini split error codes?

Understanding mini split error codes is crucial as it can expedite repairs, prevent system issues, extend the system’s lifespan, and save you from costly replacements. Keeping track of error codes is essential for maintaining your mini-split system in good condition.