Why Won’t My AC Turn On?

Although mini split air conditioning units are typically reliable, you may occasionally find yourself in a situation where your AC won’t turn on when you need it to. If this happens to you, don’t panic. It doesn’t necessarily mean your mini-split is broken or non-functional.

If your mini split AC isn’t working correctly, check for common problems like low battery power or standing too far from the unit. If you’re still left wondering “Why won’t my AC turn on?”—contact a professional repair service to help you address the issue. 

Check Your Unit’s Remote Control

Although some mini split systems may come with a fixed control panel, the vast majority rely on the remote control as your only means of accessing the unit’s settings and parameters. If your remote isn’t working correctly, you won’t be able to turn it on or off, change the thermostat, modify settings, or perform any of your mini split’s convenient functions.  

Checking your remote control before all other problems may help you find a quick, easy solution to your AC issues. Here are five questions to ask yourself when checking your AC remote’s functionality.

Are the batteries dead?

One of the simplest and most common reasons behind a non-functioning mini-split remote is their batteries are dead. Although most remotes burn a minimal amount of battery power, the power draw is constant, and batteries eventually run out, requiring you to replace them.

The life of a mini split remote varies depending on the make and model, and some are more energy-efficient than others. For example, the remote for a Gree air conditioner may not have the same power supply as an LG or a Mitsubishi remote.

You can expect a typical remote control to last between three and six months on average, assuming regular usage. Always keep spare batteries on hand, and replace them when necessary.

If you intend to stop using your mini-split for an extended period, consider removing the batteries before leaving. It can preserve the battery’s remaining power and avoid draining it while you’re away.

Are the batteries inserted correctly?

If you’ve recently replaced the batteries in your remote control, but it still doesn’t work, check that you put in the batteries correctly. Check that the battery polarity is correct and you’ve inserted them in the proper orientation. Your remote’s battery compartment should feature embossed plus (+) and minus (-) symbols representing the correct orientation.

If the remote still doesn’t work even with fresh batteries in the correct orientation, the contacts (the springy metal parts touching the battery’s extremities) may be dirty, clogged, or obstructed. Remove the batteries from the battery compartment and use a cotton swab dipped in isopropyl alcohol or a can of compressed air to remove any blocking dust, dirt, or grime.

Am I close enough to my unit?

If your remote has working batteries and seems to function correctly but fails to turn the AC unit on, it may be because the infrared (IR) signal cannot reach your mini-split. Though the maximum range of a mini split remote depends on the make and model, the average range falls around 30 feet. Check your unit’s instruction manual for your unit’s IR range.

Move closer to your mini split when operating the remote, and ensure there are as few obstacles between the remote and the AC’s receiver as possible. Obstructions on the remote’s sensor can reduce or cut the IR signal’s range entirely; make sure the sensor is clean and free of dust, dirt, and grime.

Did I press the wrong button?

Occasionally, a user error such as pressing the wrong button or command may cause the remote to behave unexpectedly. For example, you may be unable to turn the AC on or off if you accidentally navigated into a menu or activated an unrelated function. 

The best way to get out of an unwanted menu is to read the user manual and familiarize yourself with every mode and function available with your mini split remote.

What do I do if all else has failed?

If none of these quick fixes have resolved your issue or your remote control exhibits more severe signs of malfunction or damage, you may need to replace the remote entirely.

Examples of situations requiring a remote replacement:

• The liquid crystal display is partially or entirely malfunctioning even with fresh batteries.
• The batteries have leaked, and battery corrosion has seeped into the circuits.
• The housing or circuits exhibit visible signs of damage (cracks, missing elements).

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Check Your Indoor Unit

If the remote control isn’t the source of your mini split air conditioner’s issues, it may be related to the indoor unit (or one of them if you have a multi-zone system). Here’s a list of potential problems and ways to fix them:

Is there a broader power issue?

If your indoor unit is plugged in, yet you still can’t turn it on or receive any response when using the remote, verify that your house isn’t experiencing a more expansive power-related issue. This situation may include a power outage or a blown fuse.

The best way to confirm whether the issue comes from your unit or your house’s power is to check the status of your other electrical devices like your lights or refrigerator. If no other devices lack power, check your fuses and replace any blown ones.

If none of your fuses have blown, your area may be experiencing a power outage. According to the Energy Information Administration, the average length of a typical power outage is 112 minutes. Check with your local power company to obtain an estimated time for repair. If this is the cause of your AC not working, you’ll have to wait for the electricity to come back on for it to start running again. 

The Indoor Unit Is On, but Not Cooling

If your indoor unit appears to be running but isn’t blowing any cool air, there are multiple potential explanations for this symptom. Here’s how to recognize and fix them:

Is it set to the correct mode?

Although this issue most commonly happens with dual-mode air conditioners set to the heating mode, such as the LG split-system with heating and cooling modes, even a standard, cooling-only mini-split may be set in the wrong mode.

Verify that your mini split AC’s cooling function is enabled. Depending on the make and model, you may need to turn it off and then back on again. Wait a few minutes while the system restarts and check the indoor unit for cold air. If your indoor unit is blowing cold air again, it should now be functioning correctly. If not, try one of the other potential fixes.

Is the thermostat set to the correct temperature?

Another common issue is an incorrectly set thermostat setting. If your home feels warmer than usual, it may be because your AC is set too high. Use your unit’s remote control to verify the current thermostat setting, and then change it to your preferred temperature. 

Is the filter clean?

If changing your AC’s settings didn’t help, your mini-split may be suffering from dirty or clogged filters. The role of an air filter is to keep harmful airborne particles from reaching the inside of your home, improving the air quality and keeping it free of contaminants.

If the filter isn’t regularly changed, it will eventually become clogged with dust and grime, blocking airflow and preventing your air handling unit from functioning correctly. Keeping clogged filters for extended periods may reduce your indoor air quality or fail to stop contaminants from entering your indoor atmosphere, increasing the risk of health complications like allergies, asthma, or fatigue.

If your unit isn’t delivering cold air, turn it off, open it, and inspect the filter. A dirty filter typically looks darker than a clean one due to the dust, dirt, grime, hair, particulates, and other contaminants covering the surface.

Learn how to clean your filters and indoor handlers. If needed, establish a regular maintenance schedule to clean or replace your filters as frequently as necessary.

Are error codes appearing?

If there is a legitimate problem, beyond remote or filter issues, the indoor unit should display an error code. This code will help pin-point the root issue. If and when an error code appears, an HVAC contractor should be called to assist with the repair.

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Is my unit correctly sized for my room?

The size of a mini split air conditioner refers to its maximum cooling capacity when operating at full load. The size of a specific unit is expressed in BTUs (British Thermal Units). The amount of BTUs determines the ideal room size in which you should install it. 

You can determine the necessary BTUs for your household by using an online BTU calculator or dividing the number of BTUs by 20 to obtain the ideal room size in square feet. If your room falls within 10 to 15% of that value, you have the correct size AC unit. For example, a 30,000 BTU wall air conditioner unit is ideally suited for a 1,500 sq.ft. room and will work well in zones between 1,000 and 1,650 sq.ft. 

If your room is too large for your air conditioner, your unit may be working at maximum capacity yet struggle to cool its assigned zone adequately. The most common symptom is a noisy indoor unit. You can find another potential sign in your energy bills. An undersized unit works at 100% for extended periods, expending more energy and increasing your electricity consumption.

The best remedy for this issue is to replace your current indoor unit with one of the same make and model range but featuring a higher capacity.

Potentially Severe Issues

If you install the right size AC unit, maintain clean filters, and set your AC to the correct mode and thermostat temperature yet still cannot provide adequate cooling to your zone, you may be facing a more serious issue. In this case, you’ll need to check for clogging or ice or contact a professional for help. 

Is the outdoor unit clogged?

An indoor air unit can only provide cool air inside your home if the outdoor unit can pull warm air out of it. To do so, the outdoor unit’s fan and condenser must be in proper working order.

Inspect your mini split system’s outdoor unit and clean the fan, fan grille, and condenser coils. Like indoor units and air filters, you should regularly clean the outdoor unit to prevent drops in cooling performance. If cleaning the outdoor unit didn’t help, you may need professional assistance.

Is there ice inside the indoor units?

While inspecting your indoor units, you may find ice or frost formations on your indoor unit’s evaporator coils. Frozen evaporator coils indicate that your mini split has experienced a failure to regulate and circulate cool air into your home correctly.

Typical causes for frozen evaporator coils include:

• Low outside temperatures: If you leave your AC on under winter conditions and outdoor temperatures at or below freezing levels, you may cause the evaporator coils to freeze. Turn your system off during the winter to prevent it from happening.
• Improper air circulation: Typically caused by leaving indoor filters and the outdoor unit clogged for extended periods, the best way to prevent this issue is to maintain a regular cleaning and maintenance schedule.
• Damaged or malfunctioning parts: Your indoor air handler’s blower or fan may be damaged, misaligned, or otherwise failing to properly blow cold air away from your coils and into your room, causing them to freeze. The only way to fix this issue is to contact a qualified HVAC repair service.
• Insufficient refrigerant levels: Typically caused by a refrigerant leak, only a qualified HVAC repair technician can fix refrigerant leaks. Do not attempt to refill your AC with refrigerants or fix a leaky refrigerant line yourself.

If you are experiencing issues due to a frozen indoor unit, you can attempt the following steps to defrost it:

1. Before anything else, turn the thermostat setting off (disabling cooling mode) to prevent potential damage to your AC system.
2. Turn the indoor unit’s fan on, forcing it to blow warm air over the frozen coils. Do not set it to “AUTO” because this may cause the system to short-cycle.
3. Allow the coils to thaw out naturally. Do not try accelerating the thawing with a heat gun or other external heat sources.
4. Inspect your air filters, evaporator coils, outdoor unit fan, and condenser coils, cleaning them as needed. Check for refrigerant leaks, damaged parts, and other potential signs of more serious issues.
5. Once the indoor units have entirely thawed out, turn the AC back on and check back daily. If you continue experiencing issues or if you see anything requiring advanced repairs, contact an HVAC repair service.

Shop the Most Reliable Mini Split Air Conditioners at ComfortUp

ComfortUp carries a comprehensive selection of single-zone and multi-zone mini split air conditioners made by the world’s top manufacturers. 

Whether you need a single-zone unit to cool your studio or bedroom or a complete multi-zone system for your entire home, find your ideal heating and cooling solution with ComfortUp. For more information, call us at 1-855-337-0001 or contact us using our convenient online form.

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