Why Is My Mitsubishi Electric Air Conditioner Blinking Green Light?

Mitsubishi Electric is one of the leading manufacturers of air conditioning systems and other HVAC solutions. Their split unit air conditioners are highly popular across residential and commercial settings for their energy efficiency, low noise, and reliability.

However, sometimes owners face issues with their Mitsubishi Electric AC unit blinking a green indicator light. This blinking light is actually an error code that signifies something is wrong with the air conditioner.

The green indicator light on a Mitsubishi AC unit serves to provide diagnostic information to the user. A steady green light usually means the system is operating normally. However, when this green light starts flashing or blinking, it is indicating one of several possible underlying issues.

Some common reasons for your Mitsubishi electric air conditioner to blink its green light include:

  • Power voltage spikes or surges
  • Imbalance in multi-split system settings
  • Obstruction of the fan or blower
  • Problems with the power supply cord
  • Refrigerant leakage resulting in low pressure
  • Accumulated dirt and debris in air filter
  • Failure of the compressor
  • General electrical and wiring faults

Flashing green light is the AC’s way of signaling to the owner that maintenance or repair work needs to be carried out. While some problems like voltage spikes can be addressed simply by resetting the unit, others would need professional technical help.

Over-Voltage Causing the Blinking Green Light

One of the most common reasons for a Mitsubishi Electric air conditioner to blink its green light is an over-voltage or power surge passing through the unit.

HVAC equipment like air conditioners have a defined operating voltage range. In case there are sudden spikes or fluctuations in the power supply that go beyond this range, it can trip the system’s safety mechanisms.

Power surges can be caused by various factors like lightning strikes, short circuits, grid fluctuations, etc. The voltage regulators in the AC unit may not be equipped to handle such sudden spikes.

As a protective mechanism, Mitsubishi Electric ACs are programmed to detect any over-voltage conditions. When the input power exceeds the permissible range, the AC immediately shuts down operation. Simultaneously, the green light on the indoor unit starts flashing rapidly to alert the user.

This blinking of the green LED indicates that an over-voltage issue caused the air conditioner to turn off as a safety precaution. The good news is that power surges rarely cause permanent damage to the equipment.

To restart a Mitsubishi AC that is blinking green from over-voltage, the following resetting procedure can be followed:

  • Shut off the main isolator switch that controls power supply to the AC
  • Keep the isolator switch in the off position for 20-25 seconds
  • Switch the isolator back on and check if the flashing light has stopped

This disconnects the power supply for a short duration and clears out any temporary voltage spikes. The AC should be able to resume normal operation once the power returns back within nominal range.

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)

See Also  Tempstar 10 Air Conditioner Troubleshooting

Multi-Split Imbalance Causing Blinking Light

Mitsubishi Electric air conditioners are popular for their multi-split systems that allow a single outdoor unit to connect with multiple indoor units. This provides simultaneous heating or cooling across different rooms using just one external compressor.

However, in some cases, an imbalance can occur in the settings of a multi-split AC system. For instance, one indoor unit may be set to cooling mode while another unit is set to heating. The external unit can get confused trying to concurrently provide hot and cold airflows.

This kind of imbalance in the operating modes triggers the green indicator light on the indoor units to start blinking. The clashing settings disrupt the refrigerant flow and cause the system to shut down as a safety measure.

Resetting the AC power can temporarily solve the blinking issue caused by multi-split imbalance. The steps are the same as resetting for over-voltage:

  • Turn the isolator off for 20-25 seconds
  • Switch the isolator back on to resume power supply

The AC may work normally once restarted. However, the problem can recur if the imbalance in multi-split settings is not corrected.

If the green blinking light persists even after resetting, it likely indicates an underlying issue with the system settings. In such a case, it is best to call in a qualified Mitsubishi service technician to inspect and reconfigure the multi-split arrangement.

Obstructed Fan Causing the Blinking Light

Mitsubishi Electric air conditioners rely on the continuous rotation of internal fans and blowers to circulate cooled air. If the fan motor or blades get obstructed by an object, it can cause the AC to malfunction.

Some common causes for fan obstruction include:

  • Accumulated dust and debris
  • Leaves or paper getting sucked in
  • Ice formation due to low refrigerant
  • Dislodged brackets or fittings
  • Wires getting tangled in fan assembly

When the fan gets blocked, it cannot rotate smoothly to pass the air over the cooling coil and into the room. This seizes up the airflow and makes the AC unit ineffective. The electronic control board detects the obstruction and shuts down the system while blinking the indicator light.

To troubleshoot a blinking green light caused by fan obstruction:

  • Switch off and isolate the AC power supply
  • Open the front panel of the indoor unit
  • Check for any objects stuck in the fan blades or motor
  • Use a soft brush to clear any debris or dirt
  • Test the fan rotation by spinning manually
  • Close the panel, restore power and check if blinking stops

It is important not to re-power the AC unit until the fan spins freely. Foreign objects stuck in the fan can further damage the blades and motor. The blinking light should stop once unobstructed operation is restored.

Damaged Power Cord Causing the Blinking Light

The AC power supply cord delivers electricity from the mains to the components inside the air conditioning unit. If this power cord gets damaged, it can disrupt normal operation and cause the green light to blink as an error sign.

Some ways in which the power cord can get damaged include:

  • Fraying or tearing of wiring insulation
  • Cracks, cuts or perforations in the cord
  • Wires getting pinched or crimped
  • Gnawing by rodents or pets
  • Melting due to excess heat or sparks

To check and fix a potentially damaged power cord:

  • Visually inspect along the length of cord for defects
  • Check for loose plug connections
  • Use a multimeter to test for continuity in wires
  • If any discontinuity found, replace cord
  • Consult electrician if cord replacement is difficult
See Also  Lennox Air Conditioner Troubleshooting

It is hazardous to use damaged power supply cords due to risks of short circuit, electric shocks, and fires. Replacing the defective cord should stop the blinking green light if that was the underlying issue.

Refrigerant Leakage Causing Blinking Light

At the heart of any air conditioning system is the refrigerant gas that flows through the sealed piping coils. This refrigerant has important heat absorption properties that enable cooling of air.

Over years of wear and tear, the refrigerant pipes and joints may develop leaks. This causes the refrigerant pressure inside the AC system to drop steadily as the gas escapes.

When the refrigerant level falls below the optimal range, it severely impedes the heat exchange process. Sensors alert the AC control board about the low pressure, prompting an emergency shutdown. The green indicator LED also starts flashing to denote loss of refrigerant.

Fixing refrigerant leakage requires expertise in AC repair. Some approaches include:

  • Pressure Testing – Helps identify area where leak is occurring.
  • Leak Sealants – Chemical sealants can temporarily plug small leaks.
  • Brazing Repairs – Welding new metal over cracks and holes.
  • Pipe Replacement – Switching out ruptured pipes to control major leaks.

It is crucial to get low refrigerant issues fixed by qualified HVAC technicians. Adding refrigerant in a DIY manner without addressing the leak can seriously damage your AC system.

Clogged Air Filter Causing the Blinking Light

The air filter in a Mitsubishi Electric AC performs the critical function of trapping dust, allergens and debris as air passes through it. Over time, the filter can get clogged by accumulated dirt and particles.

A blocked air filter prevents proper airflow and makes the AC work harder to achieve cooling. This strains the internal components and eventually causes the system to shut off while the indicator light blinks.

Some consequences of a severely clogged air filter include:

  • Restricted airflow leading to poor cooling
  • Icing up of evaporator coil due to low airflow
  • Higher risk of refrigerant leakage
  • Straining and wear of fan motor
  • Problems in heat exchange and moisture removal

Mitsubishi recommends replacing the air filters every 4-6 months under moderate usage conditions. Higher usage or dustier environments may need more frequent filter changes.

To troubleshoot a blinking AC light caused by dirty filter:

  • Turn off and isolate the AC power supply
  • Open filter access panel
  • Slide out the filter and check for debris buildup
  • Rinse cleanable filters under tap water or replace if non-washable
  • Reinsert cleaned or new filter in proper orientation
  • Close access panel and restore power

Failing Compressor Causing Blinking Light

The compressor in a Mitsubishi Electric AC has the vital task of pressurizing and circulating the refrigerant gas in the closed-loop system. If the compressor starts failing, it can trip the AC unit and cause the indicator light to blink.

Some common reasons for compressor failure include:

  • Refrigerant leakage leading to low pressure intake
  • Burnt-out windings due to electrical issues
  • Failed capacitors disturbing compressor operation
  • Blocked condenser coils obstructing refrigerant flow
  • Mechanical breakdown due to prolonged wear and tear

A failing compressor struggles to maintain the pressurization required for refrigerant circulation. The AC system detects this abnormal operation and shuts itself down to prevent permanent damage.

However, it can be tricky to diagnose if the blinking green light is due to compressor failure or caused by an underlying issue like refrigerant leakage. HVAC technicians have specialized tools and expertise to correctly identify the root cause.

See Also  Ductless Air Conditioner Troubleshooting

In case the compressor itself is found to be faulty, solutions include:

  • Repairing damaged compressor components
  • Replacing just the failed compressor
  • Replacing the entire outdoor AC unit

Getting professional assistance is advised when AC compressor issues arise. Proper diagnostics is crucial before attempting compressor repairs or replacements.

Electrical Faults Causing the Blinking Light

The intricate electrical components and wiring in a Mitsubishi Electric AC must work properly to run the unit safely. Loose connections, burnt wiring and electrical shorts can create malfunctions.

Some common electrical issues that may cause blinking light error code:

  • Damaged or deteriorated terminal blocks
  • Faulty contactors and relays
  • Short circuit due to frayed wiring
  • Power surges frying printed circuit boards
  • Broken solder connections on controllers
  • Moisture corrosion and mold in electrical parts

Such electrical faults disrupt the power supply to AC components and pose serious safety hazards if left unchecked. The system shuts down operation and indicates the issue through blinking green light.

When electrical faults are suspected:

  • Isolate the AC power supply and turn off breaker
  • Call a certified electrician for inspection and repair
  • Look for signs of burns, corrosion and damage
  • Replace any deteriorated wiring, boards or parts
  • Check for improper connections and loose contacts
  • Restart AC once faults are fixed to stop blinking

Diagnosis and Repair of Blinking Light Issues

When a Mitsubishi Electric AC shows blinking green light, it means the air conditioner has detected some kind of fault and shut itself down as self-protection.

Here are some tips for diagnosis and repair:

  • Reset Power Supply – For minor voltage fluctuations, resetting the AC power can resolve the blinking light. This involves switching the isolator off/on or unplugging the cord.
  • Check Error Code – The number of blinks in a pattern may indicate a particular error code pointing to the type of fault.
  • Visual Inspection – Look for obvious issues like obstruction, dirt accumulation, cord damage.
  • Self-diagnosis Mode – Some models have a built-in self-check mode that displays fault codes.
  • Professional Assistance – For complex electrical or refrigerant-related faults, get expert HVAC technician help.
  • Replace Filters – Clogged filters are an easy fix by switching to a new filter.
  • Safety Checks – Ensure frayed wiring, leaks and compressor faults are fixed before restarting AC.
  • Monitor Performance – After servicing, check if AC runs without blinking light or shutdowns.

With a systematic approach of diagnosis and repair, the majority of blinking light issues can be resolved. Timely fixing of faults helps prevent costly damages.


The blinking green light on your Mitsubishi Electric air conditioner is trying to alert you about a problem that needs attention. It is the AC’s way of signaling that service or maintenance is required.

While the light itself is not indicative of the underlying issue, it should prompt the owner to proactively troubleshoot and identify the fault. Many problems like clogged filters, fan obstructions and voltage spikes can be easily fixed by DIY methods.

However, it is prudent to seek professional help for diagnosing issues like refrigerant leaks, electrical faults or compressor failure. Timely servicing prevents the problem from exacerbating and causing permanent damage.

Periodic checks and scheduled maintenance is the best way to catch problems before the AC shuts down with a blinking light. Simple steps like replacing air filters, cleaning fans, inspecting cords and connections go a long way.

Consider the blinking green indicator on your Mitsubishi Electric AC unit as a friendly reminder to give some care and attention to your air conditioning system. With proper diagnosis and servicing, you can continue enjoying the comfort and energy savings of a reliably working AC for years to come.

Leave a Reply

Your email address will not be published. Required fields are marked *