What is a P6 Code on a Mini Split? A Comprehensive Troubleshooting Guide

The P6 code on a mini-split system typically indicates a compressor high-pressure or low-pressure switch open, which could be due to a refrigerant leak, insufficient refrigerant charge, or a malfunctioning compressor. This comprehensive guide will walk you through the step-by-step process to diagnose and resolve the P6 error code on your mini-split unit.

Checking the Wiring Connections

The first step in troubleshooting a P6 error code is to ensure that all wiring connections are secure and undamaged. Start by visually inspecting the wiring between the indoor and outdoor units. Check for any loose, frayed, or damaged wires, and make sure all connections are tight and secure. Use a multimeter to test the continuity of the wires and ensure there are no open circuits.

If you find any issues with the wiring, carefully repair or replace the damaged components. Ensure that all connections are properly crimped or soldered, and that the wires are routed neatly and away from any sharp edges or moving parts.

Inspecting the Temperature Sensor

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A faulty temperature sensor on the indoor unit’s coil can also trigger the P6 error code. Locate the sensor, typically mounted on the refrigerant line or coil, and inspect it for any signs of damage or contamination. Use a multimeter to test the sensor’s resistance and ensure it is within the manufacturer’s specified range.

If the sensor is dirty, gently clean it with a soft cloth and a mild cleaning solution. If the sensor is damaged or the resistance is out of range, you will need to replace it. Consult your mini-split’s service manual for the correct sensor replacement part and installation instructions.

Resetting the Air Conditioner

Sometimes, a simple reset can resolve the P6 error code. Start by pressing the reset button on the indoor unit’s control panel, if available. If there is no reset button, turn off the power to the unit at the circuit breaker or disconnect, wait a few minutes, and then turn the power back on.

After the reset, observe the unit’s operation and see if the P6 error code reappears. If the issue persists, move on to the next troubleshooting step.

Checking the Control Board

If the P6 error code continues to appear after the previous steps, the issue may be related to a malfunctioning control board. The control board is the brain of the mini-split system, responsible for managing the various components and monitoring the system’s operation.

To check the control board, first, ensure that all wiring connections to the board are secure. If the connections are tight, you may need to have a technician inspect the control board for any signs of damage or malfunction. In some cases, the control board may need to be replaced to resolve the P6 error code.

Inspecting for Refrigerant Leaks

A slow refrigerant leak can also trigger the P6 error code. Start by visually inspecting the copper refrigerant lines, especially where they are connected to the outdoor unit, for any signs of leaks, such as oil stains or hissing sounds.

If you suspect a leak, use a leak detection solution or an electronic leak detector to pinpoint the exact location of the leak. Once the leak is identified, you will need to have a professional HVAC technician repair the leak and properly recharge the system with the correct refrigerant type and amount.

Checking the Refrigerant Charge

If the refrigerant charge is insufficient, it can cause the P6 error code to appear. A professional HVAC technician should use a refrigerant scale to weigh the refrigerant charge and compare it to the manufacturer’s specifications. If the charge is low, the technician will need to add refrigerant to the system until the correct level is reached.

It’s important to note that mini-split systems should be charged by weight, not pressure measurements, to ensure the correct refrigerant charge. Attempting to charge the system by pressure alone can lead to an improper refrigerant charge and further issues.

Pressure Testing the System

To ensure there are no leaks in the system, a professional HVAC technician should perform a full leak search with a nitrogen pressure test. This involves pressurizing the system with nitrogen gas and then using a leak detector to identify any potential leaks.

If any leaks are found, the technician will need to repair them and then recharge the system with the correct refrigerant type and amount. This comprehensive leak testing and repair process is essential to resolving the P6 error code and preventing future issues.


The P6 error code on a mini-split system can be a frustrating issue, but by following the step-by-step troubleshooting guide outlined in this article, you can effectively diagnose and resolve the problem. Remember to always prioritize safety and consider contacting a professional HVAC technician if you are unsure or uncomfortable with any of the troubleshooting steps.

By taking the time to thoroughly inspect and address the potential causes of the P6 error code, you can ensure your mini-split system is operating at peak efficiency and avoid any further issues down the line.


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