What Does EC Mean on a Mini-Split?

The “EC” error code on a mini-split air conditioning system typically indicates a refrigerant leak detection issue. This error is triggered when the system detects a drop in pressure or a freeze-up in the evaporator coil, suggesting a potential refrigerant leak. Properly diagnosing and resolving the EC error is crucial for maintaining the efficient and safe operation of your mini-split unit.

Checking for Cool Air

If cool air is still blowing out from the indoor air outlets, the first step is to check the resistance value of the T2 sensor. The T2 sensor is responsible for monitoring the temperature of the evaporator coil. Use a multimeter to measure the resistance of the T2 sensor, and compare the readings to the manufacturer’s specifications. If the resistance value is not within the acceptable range, the T2 sensor may be faulty and will need to be replaced.

If the T2 sensor is functioning correctly, but the EC error persists, the issue may be with the indoor unit’s printed circuit board (PCB). In this case, you will need to replace the indoor PCB to resolve the error.

Inspecting for Refrigerant Leakage

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If there is no cool air blowing out from the indoor unit, the next step is to inspect the system for refrigerant leakage. Start by applying a soapy water solution or a specialized leak detection fluid to the various joints and connections in the refrigerant lines. Observe for any bubbles, which would indicate a leak.

If a leak is detected, you will need to recover the remaining refrigerant, repair the leak, and then vacuum and recharge the system with the appropriate refrigerant type and quantity. Ensure that you follow the manufacturer’s guidelines and use the correct tools and equipment for this process to avoid further damage to the system.

Checking the Electronic Expansion Valve (EEV)

The electronic expansion valve (EEV) is a critical component in the mini-split’s refrigeration system, responsible for controlling the flow of refrigerant. To check the EEV, first measure the resistance of the EEV coil using a multimeter. If there is a short-circuit, the EEV coil will need to be replaced.

Next, measure the output voltage to the EEV. Compare the measured values to the manufacturer’s specifications. If the output voltage is not within the acceptable range, the outdoor PCB may need to be replaced.

Inspecting for Blockages

If the EC error persists even after addressing the refrigerant leakage and EEV issues, the problem may be due to a blockage within the system. Pay close attention to the capillary tube, as it is a common point of blockage.

To check for blockages, carefully disassemble the relevant components and visually inspect the capillary tube and other refrigerant lines for any obstructions. If a blockage is found, you may need to replace the high-pressure valve assembly to resolve the issue.


The EC error code on a mini-split air conditioning system indicates a refrigerant leak or pressure drop within the system. By following a systematic troubleshooting approach, you can effectively diagnose and address the underlying cause of the EC error. Remember to always prioritize safety, use the appropriate tools and equipment, and follow the manufacturer’s instructions to ensure the proper and safe operation of your mini-split unit.


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