Mitsubishi Air Conditioner Troubleshooting Guide

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Common Problems with the Mitsubishi Air Conditioner

Problem Possible Causes Solutions
AC Unit is Blinking Lights Loose or unsecured bottom louver clasp; Dirty air filter; Busted fuse. Refer to error code, and troubleshoot according to the detected problem.
AC is Leaking Water Blockage or clog in the condenser drain line Clean the pipes of your unit to unclog the drain line.
AC is Blowing Hot Air Dirty air filter, to broken compressors, or faulty thermostat controls. Clean the air filter, or call a technician to diagnose the problem.
AC Unit is Not Cool Enough Mismatched BTU to room size Replace the unit with a more powerful model, or move it to another room.

#1 Mitsubishi AC Unit is Blinking Lights

Your Mitsubishi aircon indoor unit will start blinking as its self-diagnosis mechanism helps it communicate a problem within the unit. This allows the aircon to immediately notify you or the technician that there's an issue with your unit that needs correcting right away.

Check the Bottom Louver

The first thing that you need to check when you run into this issue is if the bottom louver’s clasp is secure and tight. Most of the time, a loose or unsecure clasp causes the lights at the bottom right of the unit to blink. Simply put them firmly back in place and make sure the whole thing’s shut tightly and firmly. 

Troubleshoot the Issue

For other potential causes, be sure to pay attention to which LED light is blinking: the top, the bottom, or both. Afterwards, check the number of times the lights blink; this is done by counting the number of blinks in one set. For example, the bottom LED lights can blink for three times before pausing and repeating. This is considered as one set.

Troubleshoot the issue accordingly. The problem may be as simple as a dirty air filter, or as complicated as a busted fuse in the circuit breaker box. Identify the meaning of the blinking lights first, then use the owner's manual to follow a step-by-step guide to troubleshoot the issue. For any electrical issues, contact an electrician to check your circuit breaker.

#2 Mitsubishi Mini Split is Leaking Water

When your Mitsubishi mini split is leaking water through the indoor unit, the issue is most likely due to a clog. A blockage or clog in the condenser drain line in your mini split will backup the water through your unit, causing a dripping Mitsubishi mini split. A leaking Mitsubishi mini split may not generate cool air properly, and may blow warm air instead.

If you’re fixing the issue yourself, you need to take the mini split out of its wall and casing. Next, clean the pipes to get rid of the material causing the blockage — dirt, dust or frozen water. Splash the entire piping system with water to further rinse it of any particles.

Once you’re done with washing the unit, simply let the mini split air dry before you assemble everything back together. However, if you’re quite unsure of how to do this yourself, it is best to have an aircon servicing expert to deep clean your Mitsubishi mini split for you.

#3 Mitsubishi Air Conditioner is Blowing Hot Air

If your Mitsubishi air conditioner is working, but is blowing hot air instead of cold air, it may be difficult to pinpoint the source of the problem. Anything from a dirty air filter, to broken compressors, and faulty thermostat controls can affect the cooling efficiency of your unit. Zoning into one possible cause can prove to be challenging.

First, clean your air cleaning filter, and check if the setting may be on a heating mode. The issue may stem from a dirty air filter after all. If the problem persists, contact us at Luce Aircon, the best aircon service company. Make sure to get regular proper servicing to avoid experiencing the same issue again.

#4 Mitsubishi AC Unit is Not Cool Enough

If your air conditioner is emitting cold air, but it is not sufficient enough to cool the room, then the issue may simply be a mismatch between the size of your air conditioner, and the size of your room. Your AC unit may not have a powerful enough cooling efficiency to properly cool down your room. Replace the unit with a more powerful model, or move it to another room.

How to Reset Your Mitsubishi Air Conditioner

Reset Point: Circuit Breaker

First, turn your Mitsubishi air conditioner off, but keep the power cord plugged to the socket. Make your way to the breaker box, and flip the circuit breaker connected to your air conditioner. Wait for 30 seconds to a minute before flipping the switch back into its original position. Power your air conditioner back on, and the restart should be finished. 

Mitsubishi AC Troubleshooting Guide

#1 Check for Error Codes

Your Mitsubishi air conditioner should display an error code when there's a problem with your unit. Check for the error code displayed on the LED screen of your control board, Mitsubishi mini split, or remote control. Blinking lights are also considered error codes.

#2 Cross-reference with Your Owner's Manual

Once you've identified the error code, cross-check with the list of error codes in your owner's manual. You should find a full list of error codes specific to your air conditioner model, as well as a simple troubleshooting guide for each AC issue.

#3 Contact the Professionals for Repairs

Air conditioner repairs are challenging and hazardous for inexperienced homeowners. If you can't find the source of the problem with your Mitsubishi air conditioner, contact us at Luce Aircon, and one of our experienced technicians will be able to assess and fix the problem for you, as well as provide care tips to keep your Mitsubishi AC in good condition!

Whether you have the Mitsubishi mini split ACs, window-types, or centralized air conditioners, our technicians will be able to conduct proper repairs and replace any faulty parts without further damaging your unit!

Common Error Codes

Error Code Meaning
P1 Intake sensor error
P2 P9 Pipe (Liquid or 2-phase pipe) sensor error
E6 E7 Indoor/outdoor unit communication error
P4 Drain sensor error
P5 Drain pump error
PA Forced compressor error
P6 Freezing/Overheating safeguard operation
EE Communication error between indoor and outdoor units
P8 Pipe temperature error
E4 Remote controller signal receiving error
Fb Indoor unit control system error (memory error, etc.)
E0 E3 Remote controller transmission error
E1 E2 Remote controller control board error
E9 Indoor/outdoor unit communication error (Transmitting error) (Outdoor unit)
UP Compressor overcurrent interruption
U3, U4 Open/short of outdoor unit thermistors
UF Compressor overcurrent interruption (When compressor locked)
U2 Abnormal high discharging temperature/49C worked/insufficient refrigerant
U1 Ud Abnormal high pressure (63H worked)/Overheating safeguard operation
U5 Abnormal temperature of heat sink
U8 Outdoor unit fan safeguard stop
U6 Compressor overcurrent interruption/Abnormal of power module
U7 Abnormality of superheat due to low discharge temperature
U9 UH Abnormality such as overvoltage or voltage shortage and abnormal synchronous signal to main circuit/ Current sensor error.

*See our full list of Mitsubishi error codes here.

Maintaining Your Mitsubishi Air Conditioner

The Mitsubishi line of air conditioners is a leading aircon choice that will enhance your cooling experience at home or in the office. But in order to make this happen, you also need to do your part in making sure it gets the proper care and regular aircon maintenance it deserves.

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