Mitsubishi mini split air conditioners are some of the most high-quality and reliable cooling systems on the market. With innovative Inverter technology and quiet operation, these ductless systems provide excellent temperature control for any home.
However, as with any complex appliance, Mitsubishi mini splits can sometimes develop issues that require troubleshooting. Knowing how to diagnose and fix common problems can save you the hassle and expense of a service call.
This comprehensive guide will provide detailed troubleshooting tips for the most prevalent Mitsubishi mini split issues. We’ll cover the leading causes of common problems and suggest solutions to try yourself before calling a technician. Read on to become an expert at troubleshooting your Mitsubishi mini split system!
Common Problems with Mitsubishi Mini Split Units
While Mitsubishi mini splits are incredibly reliable, they can develop issues just like any other heating and cooling equipment. Here are some of the most common Mitsubishi mini split problems homeowners encounter:
- Unit not turning on
- Unit not staying on
- Insufficient heating or cooling
- Unit not turning off
- Remote control problems
- Unusual noises
- Odd smells
- Error code lights
Understanding the leading causes of each problem will help you diagnose and address them quickly. We’ll break down the most likely culprits and proven DIY fixes in the next sections.
Causes and Solutions for Common Mitsubishi Mini Split Issues
Now that you know the most prevalent Mitsubishi mini split problems, let’s explore their potential causes and solutions in more detail.
Troubleshooting Mini Split That Won’t Turn On
If your indoor or outdoor mini split unit won’t power on at all, the issue is likely with the electrical supply. Here are some things to check:
- Tripped Circuit Breaker – Check your breaker box and reset any tripped breakers related to the mini split. A power surge or overload can cause them to trip.
- Faulty Electrical Outlet – Use a multimeter to test the voltage of the outlet powering the mini split. If there’s no power, you have a bad outlet.
- Damaged Power Cord – Inspect the power cable for any cuts or loose connections. Use a multimeter to check for continuity. Replace cords with any damage.
- Faulty Remote or Thermostat – Try replacing the batteries in the remote. If that doesn’t work, you may have a bad remote or thermostat that needs replacement.
- Refrigerant Leak – Low refrigerant levels can prevent the mini split compressor from turning on. Only an HVAC technician can diagnose and repair refrigerant leaks.
Troubleshooting Mini Split That Won’t Stay On
If your mini split turns on but then quickly shuts back off, it likely can’t maintain the target temperature. Possible causes include:
- AC Unit Undersized – An improperly sized unit won’t have enough capacity to heat or cool the space. Upgrade to a unit that meets your needs.
- Dirty Filters or Coils – Clogged air filters or dirty evaporator/condenser coils prevent proper airflow. Clean or replace filters and clean coils.
- Frozen Evaporator Coil – Very low temperatures can cause the evaporator coil to freeze. Raise your thermostat a few degrees.
- Faulty Thermostat – If your thermostat isn’t calibrated right, the unit can’t maintain the set temp. You’ll need a new thermostat.
- Refrigerant Leak – Low refrigerant makes it impossible for the unit to provide consistent heating or cooling. An HVAC tech should assess and fix any leaks.
Troubleshooting Lack of Heating or Cooling
If your Mitsubishi mini split isn’t providing adequate heating or cooling, it’s likely an airflow, temperature setting, or sizing issue. Potential causes include:
- Wrong Temperature Setting – If the thermostat isn’t in auto/heat mode, the unit won’t heat properly. Make sure settings are correct.
- Dirty Air Filter – A clogged filter reduces airflow over the coils, limiting heating and cooling capabilities. Replace the filter.
- Undersized Unit – An improperly sized unit won’t have the BTU capacity to sufficiently heat or cool your space. Upgrade to a bigger unit.
- Dirty Outdoor Unit – Dust, leaves and debris can settle on the outdoor unit, reducing airflow. Carefully clean the unit with water.
- Frozen Evaporator Coil – Extremely cold settings can cause the coil to freeze, blocking airflow. Raise the temperature.
- Refrigerant Leak – Low refrigerant levels directly impact the unit’s ability to properly heat and cool. An HVAC technician will need to assess and recharge the refrigerant.
Troubleshooting Mini Split That Won’t Turn Off
If your indoor unit continues running even when powered off, it could signify an electrical or refrigerant issue:
- Faulty Wiring – Incorrect or defective wiring can send continuous power to the blower fan. An HVAC technician should diagnose the wiring.
- Refrigerant Leak – Very low refrigerant levels can cause the unit to run nonstop trying to reach the set temperature. Have an HVAC technician repair any leaks and recharge the system.
Read more:
Why Your Frigidaire Air Conditioner Compressor Isn’t Turning On
Why Your Frigidaire Air Conditioner Is Not Cooling (And How To Fix It)
Why Your Maytag Bravos Dryer Won’t Start (And How to Fix It)
Troubleshooting Mini Split Remote Problems
If your remote isn’t turning the unit on or off, try these tips:
- Out of Range – The remote only works when you’re close to the indoor unit. Move closer and point the remote at the receiver.
- Dead Batteries – Try replacing the batteries in the remote. Make sure they are new and facing the correct direction.
- Improperly Installed Batteries – Check that the batteries are properly seated in the remote per the instructions. Improper battery installation can prevent proper power flow.
Other Common Mitsubishi Mini Split Issues
In addition to operational problems, Mitsubishi units may develop other quirks like strange noises, smells or error codes. Here’s how to troubleshoot those issues:
Troubleshooting Unusual Noises
Some noises are normal, while others may signify problems:
- Clicking/Cracking – This is normal expansion and contraction of plastic parts. No action needed.
- Hissing – Normal sound of refrigerant flowing through the lines. No action needed.
- Buzzing – May indicate an electrical issue. Have an HVAC technician inspect the wiring.
- Popping – Normal sound of automatic defrost cycles. No action needed.
Troubleshooting Odd Smells
Unusual odors could arise from mold, mildew or refrigerant leaks:
- Musty, Sour Smell – Indicates mold buildup in condensate drain or coils. Clean drain lines and condenser coil.
- Fishy Smell – Signals a refrigerant leak. Have an HVAC technician inspect and seal any leaks.
- Vinegar or Sweet Smell – Also indicates a refrigerant leak. Contact an HVAC technician immediately.
Troubleshooting Error Code Lights
Consult your owner’s manual to interpret any error code lights. Here are some common ones:
- E0 – Remote control error
- P1 – Faulty intake air sensor
- P4/P5 – Condensate drain line clog
- P6 – Evaporator coil fault
- P8 – Abnormal coil temp or refrigerant flow
- P9 – Communication error
Most codes can be cleared by resetting the unit. If error persists, contact Mitsubishi support or an HVAC technician.
Tips for Troubleshooting Mitsubishi Mini Splits
Follow these best practices when diagnosing and repairing your Mitsubishi mini split:
- Locate the error code label and owner’s manual to interpret any displayed error codes or lights. Understanding the code meaning is key to diagnosing issues.
- Try resetting the unit to clear any temporary error codes before doing extensive troubleshooting. Resetting often resolves intermittent errors.
- Always check your home’s circuit breaker box and reset any tripped breakers related to the mini split. This can restore power to a non-responsive unit.
- Inspect, clean or change dirty air filters on a regular basis. Clogged filters are one of the most common causes of underperformance.
- Use a mild detergent and sprayer to carefully clean the condenser and evaporator coils if they appear dusty or dirty. This removes debris that can block airflow.
- Leave refrigerant leaks, electrical problems and thermostat issues to experienced HVAC technicians. Attempting complex repairs yourself can make problems worse or void warranties.
- Schedule annual maintenance checks by an HVAC company to keep your unit running efficiently and prevent bigger problems down the road.
Conclusion
Troubleshooting common Mitsubishi mini split issues like insufficient heating or cooling, error lights, strange noises and remote control problems is much easier when you understand their root causes. While complex repairs should be left to HVAC professionals, many basic problems can be resolved yourself by following the troubleshooting tips outlined in this guide.
With a little preventative maintenance and quicker diagnosis of minor issues, you can maximize the performance and lifespan of your Mitsubishi ductless heating and cooling system. Don’t hesitate to contact a trained technician for any problems that require extensive electrical, refrigerant or thermostat repairs.
