There are multiple reasons your AC unit is flashing a red or green light. Different air conditioning brands may have different flash codes, which is why it is essential to safely store away your owner's manual when you first install your air conditioning unit for your reference.

Some codes are universal, such as a blinking red light which often indicates a problem with the internal mechanisms of your air conditioning unit. The flashing light informs you that the system has detected a problem that needs to be inspected immediately. Other light codes are as follows:

Causes of Red and Green Lights on Air Conditioner

1. Solid Green Light

A stagnant green light on your AC system simply connotes that your air conditioner is running smoothly without any issues detected. However, if the green light is on even while your AC unit isn't running, then there may be a miscommunication between the control panel and your AC unit that you need to have checked.

2. Solid Red Light

If your AC unit is turned off and flashes a stagnant red light, then it simply means your AC unit isn't running. Alternatively, it may also indicate a system start-up or shutdown if you press the power button on your control panel or remote control.

3. Flashing Green Light Only

Sometimes, the AC may be flashing green lights on your unit, which is commonly an indicator of electrical, unit, or gas valve problems.

• Overvoltage - When the cooling system detects an overvoltage problem, the aircon will go into a fail-safe mode to protect the unit, and your home, from any disastrous electrical accidents. The light will then flash green, altering the problem, before the unit starts to shut down.
• Outdoor Unit - Another common reason for a green, blinking light is an issue with the outdoor unit. Anything from blocked vents to faulty condensers and pressure switches may cause a flashing green light to inform the user of a problem.
• Mode Settings - Multi-split aircon systems may have different mode settings installed in each indoor unit. When this happens, the indicator light in the main control panel would start blinking green as the cooling system cannot make sense of the differing mode settings. Check each unit to find the problem.
• Refrigerant Leak - The flashing light may also indicate a problem with the coolant, specifically low refrigerant levels due to a leak in the pipes. This may be accompanied by the unit blowing warm air instead of cool air, water leaks, and frozen evaporator coils.

4. Flashing Red Light Only

Blinking means there is an issue with your air conditioning system, but a red, blinking light may indicate a major problem that needs immediate attention.

• The Outdoor Unit Has Shut Off - A light flashing red may indicate the outdoor unit has stopped working for several reasons. There may be debris blocking the outdoor vents, or the compressor, condenser coil, or fan may have malfunctioned.
• Air Filter Needs Cleaning - In some units, the red, flashing light may simply indicate a dirty air filter. This can be easily remedied at home by cleaning the air filter and evaporator coils. Use soapy water to clean the filter, and vacuum the evaporator coil while the aircon is shut off and unplugged.
• Tripped Circuit Breaker - A tripped breaker may be the most common cause of a light blinking red on your unit. Check the circuit board for any tripped breakers, and switch them back in place to solve the issue. You may need to contact an electrician if your unit keeps tripping the circuit breaker.
• Other Technical Malfunctions - An air conditioner light blinking red indicates a plethora of malfunctions. Anything from a dirty unit to problems with the circuit board may cause red, flashing lights. For this, it is best to contact a technician to find and fix the issue.

5. Flashing Both Green and Red Light Simultaneously

If your unit is flashing both red and green lights, then the issue is most likely with water flooding the system due to a clog in the condenser pipes, a frozen AC, or other causes. This is often accompanied by water dripping or leaking out of your unit. Shut off the unit, and contact us at Luce Aircon to consult with an AC expert.

Troubleshooting Guide

Use Your Senses

A blinking light may or may not be a cause for alarm - it all depends on the brand and model of your unit. The best way to figure out if the flickering light is a cause for concern is to read the manual and use your senses. See if the unit is dirty, clean the filter, and check if that solves the problem.

Otherwise, listen for any strange noises, notice any foul smells, and check if the air coming from your air conditioning unit is warm, not cold. A flashing light combined with any of these symptoms indicates an underlying problem with your unit.

Shut the Unit Down

When in doubt, shut the unit down, and unplug the aircon. This will avoid any further damage to your unit, and make it safe for you to inspect the interior. Even when your unit is working properly, there may be an issue that needs immediate attention in the inner workings of the unit.

Contact a Professional Technician

The best way you can solve any aircon problem is by consulting with an experienced HVAC technician at Luce Aircon. Whether you've lost your error code manual, or you can't make sense of the blinking lights on your AC, our professional technicians will be able to diagnose and repair any aircon problem for you!

Check out our article on how to fix the aircon status light blinking.