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What Is A P8 Code And How To Fix It On A Mitsubishi Mr. Slim?

What Is A P8 Code And How To Fix It On A Mitsubishi Mr. Slim?

When you attempted to turn on your Mitsubishi Mr. Slim ductless split AC, a P8 error warning appeared. What does this code indicate, and how can it be fixed? For your convenience, we looked into these worries, and this is what we discovered.

A P8 error number on a Mitsubishi Mr. Slim ductless air conditioner typically denotes a problem with the outdoor condenser. There are numerous possible origins for the problem. By observing how the LEDs on the outdoor PC board behave, you can determine the root of the problem message. Examples include:

  • Flashing LED 1: Compressor Command Phase Detected
  • Flashing LED 3: Operation Sensor Short or Open
  • Flashing LED 6: 4-Way Valve Is On Switch 26C

What Does A Mitsubishi Mr. Slim Split AC’s P8 Error Code Mean?

What Is A P8 Code And How To Fix It On A Mitsubishi Mr. Slim?

If your Mr. Slim’s remote displays a P8 error message, you should inspect the PC board in the exterior condenser. Here, watch how the LEDs act. Finding the root of the issue might be aided by doing this.

Following are some potential arguments in favor of the P8 code:

Flashing LED 1: Compressor Command Phase Detected
In specifically, the Mr. Slim AC’s electrical setup uses a 3-phase framework, and this particular issue typically results from an erroneous installation of the AC. However, one of the phases is either absent or improperly linked.

Take notice that if the system has adequate wiring, a 3-phase electrical framework typically functions. In this method, each phase can handle the air conditioner’s relatively large load.

Ways To Fix
The P8 error notice may be eliminated and the AC’s regular operations might be resumed by rewiring the outside condenser’s motor. Before beginning this assignment, make sure you have enough electrical experience and knowledge. Otherwise, ask a seasoned technician in the field for assistance.

However, if you want to proceed, particularly if you’re connecting the Mr. Split AC to a single-phase power source, adhere to these general instructions:

Step-By-Step Guide

  1. Make an U1 connection from the capacitor’s appropriate terminal to the AC’s motor.
  2. Connect the motor’s positive terminal to the capacitor by way of the electrical network in your house.
  3. Connect the AC’s motor to the connection created in the previous step using a V1 connection.
  4. Through the negative terminal of the AC’s motor, establish a W1 connection with your home’s electrical system.

Verify the security of each connection you make. The P8 error message could continue due to loose wiring.

Flashing LED 3: Operation Sensor Short Or Open
Typically, a P8 error message with a flashing third led on its exterior PC board indicates a high-pressure safety issue. It indicates that the pressure at the external condenser unit is very high. A faulty fan motor or a damaged refrigeration circuit are just two possible causes for this issue.

Ways To Fix
You’ll require:
Hex or Allen wrench
substitute fan motor

Step-By-Step Guide

  1. From the circuit breaker it is attached to, turn off the AC.
  2. Take off the front panel of the air handler.
  3. Carefully remove the electrical box.
  4. Pull the drain hose out.
  5. Carefully remove the nozzle assembly.
  6. The line flow fan and the blower motor’s hex screw should be removed.
  7. The heat exchanger’s mounting screws should be removed.
  8. Open the cap of the heat exchanger a little.
  9. Install the new fan motor after removing the old one.
  10. Reassembling the Mr. Slim AC requires following the same processes in reverse.
  11. To see if the error code remains, turn on the air conditioning.

If you want a visual explanation of this process, you can also watch this video. The guys executing the replacement task do a decent job of demonstrating the steps required to change a Mr. Slim’s fan motor in the accompanying clip, despite the fact that it isn’t in English:

Flashing LED 6: 4-Way Valve Is On Switch 26C
The P8 error notice could be brought on by a discharge thermistor. But low refrigerant levels or a defective assembly could be the primary causes of this problem.

Ways To Fix
To identify the root cause of the P8 code, examine the thermistor and the components close by. Afterward, you can continue with the remedy by taking the right actions based on your discoveries.

You’ll Require:
Multiple gauges
HVAC refrigerant

Step-By-Step Guide

  1. From the circuit breaker it is attached to, turn off the AC.
  2. the blue hose to the access port on the outdoor condenser unit.
  3. The yellow hose should be connected to the AC refrigerant bottle.
  4. Open the “Low”-marked valve on the refrigerant container after it has been opened.
  5. Once the gauge’s needle hits roughly 120 PSI, shut off the low valve.
  6. Till the needle remains in the suggested location, repeat steps 4 and 5 once more.

How Long Is The Life Of A Mitsubishi Mr. Slim?

Split air conditioners, like the Mitsubishi Mr. Split, typically endure between 8 and 18 years. The lifespan of the appliance, however, may be influenced by various circumstances. Regular upkeep and care are essential for extending the lifespan of your air conditioner.

Two Substitutes For The Mitsubishi Mr. Slim
You could be considering replacing your Mitsubishi Mr. Slim at this time. This idea might cross your mind if the cooling unit is frequently giving you issues, such as the P8 code. If so, the following are great options for your new ductless split AC:

1. Senville Mini Split AC And Heat Pump SENL-09CD-16

What Is A P8 Code And How To Fix It On A Mitsubishi Mr. Slim?

With its product, Senville brings smart AC features to homes that desire them. The commands that are compatible with Alexa are one feature worth noticing. It allows customers to remotely operate the AC using voice commands and Amazon’s advanced artificial intelligence (AI).

The built-in heat pump of this particular tiny split AC is an additional feature. Thus, regardless of the season, consumers can benefit from this device’s cooling and heating capabilities.

2. Ductless Mini Split AC By Cooper & Hunter

What Is A P8 Code And How To Fix It On A Mitsubishi Mr. Slim?

Check out this device if you or your visitors find the sound of AC motors to be unpleasant. The whisper technology used by the brand is utilized in this specific micro split air conditioner. The feature encourages silent operations, making it possible that it would be perfect for business applications.

Additionally Wi-Fi compatible, this AC allows you to use an app to regulate its operations.


Avoid attempting to repair your Mitsubishi Mr. Slim before identifying the P8 error code’s root cause. After determining the reason, take the necessary do-it-yourself steps to address the issue at its root. If you don’t feel confident, experienced, or skilled enough to do the essential task, seek a reputable AC specialist for assistance.

What Is A P8 Code And How To Fix It On A Mitsubishi Mr. Slim?

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Written by HVAC Contributor

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