Mini-Split Compressor Not Turning On

If your mini-split is not working, there can be a lot of possible reasons. But if the system is not turning on at all, your compressor may be to blame. We’re not talking about a case of changing the batteries in your mini-split remote or changing the thermostat settings. An issue with your compressor is much more serious.

The mini-split compressor is located in the outdoor mini-split heat pump, also known as the condenser unit or condensing unit. The compressor is an integral part of the refrigeration cycle that cools or heats your home. Like your heart circulates blood throughout your body, the compressor is responsible for circulating and pressurizing the refrigerant in your unit, so the refrigerant can carry and release heat.

If your compressor isn’t kicking on, your ductless system can’t heat or cool your home. There are a few main reasons for your mini-split compressor not turning on, including:

• Low refrigerant issues triggered a pressure switch to shut off the compressor.
• The compressor overheated and tripped a breaker.
• The start capacitor that helps the compressor start has failed.
• The compressor has failed.

If the compressor or start capacitor has failed, you can’t fix that yourself. You can’t fix a refrigerant leak, either. But there are a couple of things you can check before calling an HVAC professional.

First, check to make sure the system has power. Find the circuit breaker box in your house. Check to see if any breakers are tripped. Hopefully, your HVAC installer marked the breaker that controls your mini-split heat pump.

If the breaker for the heat pump is tripped, call for HVAC service. There may be a problem with the unit that caused the breaker to trip. Resetting the circuit breaker and restarting the unit could cause further damage.

Inadequate airflow can cause the compressor to struggle and even shut down. Check the mini-split air filters in each indoor unit, especially if you can’t remember the last time you checked them. Clean them, let them dry thoroughly, and then replace them.

Try turning the system on again. If the system still doesn’t start, it’s time to call for HVAC repair service. They’ll troubleshoot the issues and make the needed repairs to get your space comfortable again.

You depend on your mini-split system to keep you comfortable. Whether you have a single mini-split AC unit to cool the attic or garage or a multi-zone mini-split system to heat and cool the whole house, maintenance matters.

To keep your system running smoothly, clean the reusable filters on each indoor mini-split unit regularly to help prevent problems with your ductless HVAC system. Dirty or clogged filters can cause issues with your mini-split heating and cooling system, including:

• Inadequate or no cooling
• Inadequate or no heating
• Water leakage
• Early wear and tear on the ductless system, including the compressor

Don’t forget the ductless heat pump outside. For the best airflow, keep the unit clear of debris such as tree pollen, leaves, or twigs. Trim shrubs or other plants to keep them at least two feet away from the unit. 

Schedule professional ductless mini-split maintenance at least once a year for a mini-split air conditioner and twice a year for a ductless mini-split heating and cooling system - each spring and fall is a good rule of thumb. A maintenance check can find problems while they’re small and fix them before they become bigger issues.

Regular maintenance can also help prolong the life of the system. Failure to practice regular maintenance can lead to early wear and tear, and early failure of parts.

Schedule maintenance with your mini-split installer if your mini-split HVAC system is still under warranty.  Whatever you do, make sure you work with an HVAC company that has extensive experience installing and repairing ductless heating and air conditioning systems.

During the maintenance visit, the HVAC technician should:

• Inspect and clean the outdoor ductless heat pump and the indoor mini-splits.
• Test system operation.
• Check for refrigerant issues.
• Check electrical connections.
• Make minor repairs.

Are you a new homeowner or new to the area and not sure who to call? Read our blog on finding the right HVAC contractor near you.

Anne Fonda, Content Writer at Trane Technologies

A Content Writer with Trane Technologies, Anne Fonda researches topics and writes for Trane® and associated residential HVAC brands. She works in collaboration with Trane Technologies subject matter experts, offering easy-to-understand, informative content on complex topics. Her goal is to help consumers make informed decisions on the products and services they need.

She has written for HVAC and other service provider websites for over 16 years. Before transitioning to web content writing, Anne had a 14-year stint as an award-winning journalist. She graduated cum laude from the University of Missouri-Columbia School of Journalism. When she’s not working, Anne enjoys playing word games, reading, gardening, spending time with family, and visiting gardens and museums.

Expert review by Kimberly Sexton, Senior Systems Engineer

Understanding Your Trane/Mitsubishi Mini-Split Remote

Mini-Split Smells: Causes and Solutions

Do Mini-Splits Have Filters?

Do Mini-Splits Turn Off When Temperature Is Reached?

Mini-Split Leaking Water

Mini-Split Not Cooling

Mini-Split Not Working In Heat Mode

Mini-Split Refrigerant Issues

What Size Mini-Split Do I Need?