Comprehensive Guide: How to Get Fault Code on MRCOOL Remote


Troubleshooting MRCOOL ductless mini-split systems can be a daunting task, but understanding how to retrieve fault codes from the remote can be a game-changer. This comprehensive guide will walk you through the step-by-step process of obtaining fault codes on your MRCOOL remote, providing advanced technical details and expert-level insights to help you diagnose and resolve any issues with your system.

Turning Off the System

how to get fault code on MRCOOL remote

The first step in retrieving fault codes on your MRCOOL remote is to turn off the entire system. Begin by turning off the air handler and then flip the breaker. It’s crucial to wait for approximately two minutes to allow the system to reset completely before proceeding.

Checking for Signal Interruptions

If the error code appears again within three seconds, it’s likely a control board issue. In this case, you’ll need to check the wiring connections between the indoor and outdoor units. Ensure that the wire numbers on both units match the corresponding connections.

Using a Voltmeter

If the wiring appears to be correct, it’s time to use a voltmeter to check the electrical components. First, measure the AC voltage between L1 and L2 on the condenser. Then, check the AC voltage on wires 1 and 2 going to the air handler.

Voltmeter Specifications

When using a voltmeter, it’s essential to choose a digital model with an accuracy of at least 0.5%. This level of precision will ensure that you obtain accurate readings, which is crucial for proper diagnosis.

Measuring DC Voltage

If you still can’t identify the issue, the next step is to measure the DC voltage between terminals 2 and 3 on the indoor unit. Place the black lead of the voltmeter on terminal 2 and the red lead on terminal 3.

Interpreting the Voltage Readings

If the voltage reading is fixed and close to zero, you’ll need to check the wiring connection from the indoor terminal to the indoor primary control board. However, if the voltage is alternating between negative and positive, it’s an indication that the indoor primary control board needs to be replaced.

Checking the Indoor Primary Control Board

The indoor primary control board is a critical component in the MRCOOL ductless mini-split system. If the DC voltage readings indicate an issue with the control board, you’ll need to replace it to resolve the problem.

Contacting Technical Support

If you’ve followed all the steps and are still unable to identify the fault code or resolve the issue, it’s time to reach out to MRCOOL’s technical support team. They have the expertise and resources to provide further assistance and guidance.

Common Fault Codes

Some of the most common fault codes encountered with MRCOOL ductless mini-split systems include:

Fault Code Description
E1 Communication error
E3 Fan motor and air handler out of control
P1 Over voltage or under voltage
P4 Inverter compressor drive error


  1. How to Troubleshoot an EL 01 Error Code on 4th Gen MRCOOL DIY…
  2. Mr Cool DIY error code P6 bypass/fix – YouTube
  3. What Are Error Codes? – MRCOOL DIY Ductless Mini Split – YouTube
  4. What is an E1 Error Code? – MRCOOL DIY Ductless Mini Split
  5. What Is A P1 Or P4 Error Code? – MRCOOL DIY Ductless Mini Split

By following the detailed steps and technical specifications outlined in this guide, you’ll be well on your way to successfully retrieving fault codes on your MRCOOL remote and troubleshooting any issues with your ductless mini-split system.