What to do when your mini split AC won’t turn on

Your mini split AC is a lifesaver when things heat up, keeping your home nice and cool. So, if you hit the power button and zilch happens, it’s totally frustrating and maybe a bit alarming. We’re here to help you figure out what’s going on and walk you through some fixes you can try yourself. In this article, we’ll lay out clear steps to troubleshoot power issues, check out the electrical stuff, and point out common parts that might be acting up.

The information in this article may not apply exactly to your specific appliance model. For the most accurate guidance, it’s best to check your manufacturer’s documentation or reach out to us if you have any questions.

Why your mini split AC won’t turn on

If your mini split air conditioner isn’t turning on, it doesn’t always mean something major is wrong. Often, it comes down to something simple. Here are the most likely reasons:

• Power issues: Check for a tripped breaker or blown fuse. Make sure both indoor and outdoor units have power.

• Dead remote or wrong settings: Replace remote batteries and make sure it’s set to “Cool” or “Auto,” not just “Fan.”

• Dirty air filter: A clogged filter can cause the system to shut down for safety. Clean or replace it.

• Blocked drain or float switch triggered: If the drain line is clogged, the float switch may stop the unit from turning on.

• Low refrigerant or pressure problem: The system might stay off to avoid damage if refrigerant is too low.

• Communication error between units: Loose or damaged wiring can stop the indoor unit from signaling the outdoor unit.

• Bad capacitor or control board: Electrical components like capacitors or control boards can fail and prevent startup.

• Startup delay: After a power cycle, mini splits often have a 3–5 minute delay before restarting.

Safety precautions   

Safety should always be a priority when working on any appliance. Here are a few practical tips to help you stay safe:

• Turn off the power to the appliance by unplugging it or switching off the circuit breaker before starting any maintenance or repairs. This protects you from the risk of electric shock.
• Wear insulated gloves to shield your hands from sharp edges, pinching hazards, or debris.
• Work at a steady pace and take your time to avoid accidents or injuries.
• Make sure your workspace is well-lit so you can clearly see and access the parts you’re working on.
• Keep the area clear of clutter, and ensure children and pets stay out of the workspace.
• Never handle internal parts with wet hands. Check that both your hands and the work area are completely dry.
• Refer to your appliance’s user manual for any specific instructions or safety guidelines related to the part or repair.
• Handle parts gently to avoid damage to the appliance or potential injuries from applying too much force.
• Use safety glasses when dealing with chemicals, dust, or large debris to protect your eyes from harm.
• If the appliance was recently used, give it enough time to cool down before working on any heated components.
• Take photos or notes of wiring connections and terminals before disconnecting anything to make reassembly easier.
• Avoid touching exposed wires or terminals. If you must handle wires, use non-conductive tools or wear insulated gloves to minimize the risk of electrical shock.

Check your power supply

Your mini split AC needs a reliable power source to run. Even if everything looks fine at first glance, there might be an issue with the electricity. Before diving into more complicated repairs, try these steps to rule out any simple electrical glitches.

1. Make sure the outlet or dedicated AC circuit is working: See if your mini split is plugged into a functioning outlet or its own circuit. Plug in something else, like a lamp, to the same outlet to check if it’s getting power.
2. Reset your circuit breaker: Head to your home’s electrical panel and find the breaker linked to your AC unit. It might be flipped to “OFF” or stuck halfway. Switch it all the way to “OFF,” then back to “ON” to reset any tripped breakers.
3. Check the power connections: Ensure all external power connections to both the indoor and outdoor units are secure. Look for signs of damage or corrosion on wires and terminals.
4. Measure the voltage (if you’re comfortable with it): If you’re handy with a multimeter, carefully check the voltage at the AC’s power input. A reading that’s way off might point to a bigger electrical issue in your home or the AC system.
5. Look at external disconnect switches: Some systems have disconnects near the outdoor unit. Make sure any switches are in the “ON” position, they can get turned off by accident.

Inspect the remote and control panel

Most mini split ACs come with a remote that talks to the indoor unit. If the remote’s signal isn’t reaching your AC, maybe due to weak batteries or other issues, the unit won’t respond. Sometimes, the wall-mounted control panel can act up too. Here’s how to check that everything’s working as it should.

1. Swap out remote batteries: Put in fresh batteries. Weak batteries can result in a feeble signal or no signal at all.
2. Clean the remote sensor: Both the remote and the indoor unit have IR (infrared) sensors. Dirt or grime can mess with the communication. Gently wipe both sensors with a soft cloth.
3. Use the manual power button: Many mini splits have a small power button on the indoor unit. Press it to see if the AC starts up. If it does, the remote or its sensor might be the issue.
4. Check the control panel or thermostat: If your mini split uses a wall-mounted control panel instead of a remote, make sure all the settings are correct and there aren’t any obvious signs of damage or loose wires.
5. Verify app connectivity (if you’ve got it): Some modern units are controlled via smartphone apps. Ensure the app is connected properly and the unit’s Wi-Fi module (if it has one) is working right.

Investigate the condensate pump or drain system

Your mini split AC probably uses a condensate pump or drain to get rid of moisture it collects while cooling. If the pump’s not working or the drain line is clogged, the system might prevent itself from starting up to avoid water damage. Checking out your condensate system is an easy way to make sure excess moisture isn’t keeping your AC from running.

1. Find the pump or drain tube: Depending on your model, the drain tube usually runs from the indoor unit to the outside. If gravity isn’t enough, there might be a condensate pump near the indoor unit.
2. Look for clogs or kinks: Make sure the drain tube isn’t blocked by gunk like algae or dirt, and that it isn’t kinked. A blocked drain can trigger a float switch that tells the system not to start.
3. Check the float switch: Some pumps have a float that rises with the water level. If it gets stuck or broken, it can send a false alarm. Gently move the float to see if it moves freely.
4. Inspect the drain pan: Some units have a safety float switch in the drain pan that shuts off the system if water’s detected. Ensure the drain pan isn’t full and the switch isn’t stuck.
5. Test the pump: If you’re comfortable, you can temporarily power the pump to see if it runs. Do this carefully, following electrical safety rules. If the pump doesn’t run at all, it might need to be replaced.
6. Clear the drain line: Use a small brush or something similar to clean out any crud inside the drain line. Flushing it with water (if you can) often solves clog-related issues.

Examine internal controls, fuses, and breakers

If the easy checks don’t do the trick, the problem might be inside the unit, like with fuses or circuit boards. Many mini splits have an internal fuse or breaker to protect against power spikes. If these fail, your AC won’t turn on.

1. Access the indoor unit: Turn off the AC breaker in your main electrical panel to avoid any shocks. Then, remove the cover or panel on the indoor unit that hides the electrical components.
2. Find the fuse or breaker: Some mini splits have a fuse inside the control panel. Others have a breaker switch you can reset. Check your appliance’s manual or the manufacturer’s instructions to locate these parts.
3. Look at the fuse: A blown fuse often has a broken filament or looks dark and cloudy. If you see this, replace it with a fuse that’s exactly the same.
4. Use a multimeter to double-check: If you don’t see obvious damage, set your multimeter to check continuity. Touch the probes to the fuse terminals. If there’s no continuity, the fuse is blown. Swap it out and turn the power back on.
5. Reset the internal breaker (if there’s one): Some mini splits have a tiny breaker switch on the circuit board or near the control area. Make sure to flip it all the way OFF, then back ON.

We’re here to help

If you need any replacement parts for your appliances, you can enter your model number at AppliancePartsPros.com to locate and order them. Most orders arrive in just two business days, and we have tons of great information in our repair help section and YouTube videos to help you troubleshoot.

Stay connected with the latest DIY tips, tutorial videos, and repair guides by following us on Facebook, Instagram and Twitter. We love hearing about your repair stories and successes. If you need more help or want personalized guidance, feel free to reach out to us. Let us know how we can help you tackle your next project with confidence.