Troubleshooting Guide: When Your Mini Split Isn’t Heating

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By Debarghya Roy

Is your mini split not heating correctly? Read on to discover how to change the settings and inspect the system.

What are the Common Problems with Ductless Mini-Splits?

Ductless mini-splits are a great way to heat and cool small spaces. But, they can come with some issues. Let’s look at some of these and what can be done.

mini split not heating

Common problems and solutions are given in the table below,

Common problems Solutions
Insufficient Heating or CoolingClogged air filters, low refrigerant levels, or faulty sensors can cause this. Clean or replace the filters, check for leaks, and reset sensors for a solution.
Electrical ProblemsWiring and electrical connections can cause the system to malfunction. Professional help is needed to diagnose and fix this.
Noisy OperationLoose parts or a dirty fan motor causes noise. Tighten fasteners and clean fan blades to fix it.

The following are the reasons why mini split heat pumps are not heating up.

Ductless Mini-Splits Refrigerant Leak

A refrigerant leak could be the cause of reduced content in a mini-split system. These leaks are marked by a decline in heating efficiency and might lead to major wear and tear. 

It’s important to pay attention to any signs of decreased performance or frequent maintenance issues.

  • Detecting and repairing the refrigerant leak immediately. The leakage may be due to cracks or holes from long-term usage or inadequate servicing and maintenance. 
  • Visual inspections are often used to find the leak. This includes looking for oil stains, damp spots, and hissing or bubbling sounds near the evaporator coil.
  • Neglecting a refrigerant leak can have severe consequences. 
  • These include reduced energy efficiency and unit lifespan, plus environmental pollution due to hazardous substances released.

Ductless Mini-Splits Defrost Issue

Ice building up on the outdoor coil of the mini split unit can cause Defrost Issues, hindering heating performance. 

This usually happens when it’s colder outside or there’s not enough airflow. So, you need to clean the unit regularly. 

Dirty filters and clogged fan blades can make the ice build-up worse. Keep the outdoor unit ventilated and clean those components.

Check for refrigerant leaks and electrical faults, these could be the source of the issue. Setting a defrost timer to melt ice will increase the mini split’s lifespan.

Ductless Mini-Splits Low Refrigerant Charge

It’s essential to act fast if your mini-split system isn’t generating heat. 

Low refrigerant pressure is likely the cause this could be from a leak, not enough supply at installation, or incorrect charging.

Engage an expert technician to determine the root cause and fix it. Don’t ignore the issue or else it can lead to costly repairs.

Avoid harm to your unit by scheduling maintenance checks with a professional.

Ductless Mini-Splits Air Filter Clog

A clogged ductless mini-split air filter can lead to blockage of air flow, causing inadequate heating. 

Regular cleaning and replacing of filters can prevent such issues. Ignoring these can result in air contamination, airflow restriction and threaten family health and safety.

Mini-splits are used for household purposes from heating to cooling rooms and maintaining air quality. Optimal functioning is necessary for efficient use. 

Why is Your Mini-Split Blowing Cold Air?

It might be blowing cold air, the thermostat may be too low or set to cool, a dirty air filter, refrigerant leak, faulty compressor or fan motor, or improper installation could be the cause.

To fix it, check the thermostat and air filter. If they’re okay, it’s time to call a pro

It’s best to pick an experienced HVAC contractor, for proper installation and the best performance.

Mini-Split is Not HeatingThe mini-split system has trouble providing enough heat. To fix this, check if it’s in heat mode and the remote control temp settings are right. Check the air filter isn’t blocked by pet hair or debris. Look for a refrigerant leak or compressor issue. This needs a licensed HVAC pro.Regular maintenance will keep it working well and stop other issues. Homeowners often struggle to diagnose and fix these issues. But proper troubleshooting and care can make it last.One example: a mini-split with poor heating in freezing temps. Wiring connections and insulated lines were at fault. Fixing these fixed the issue without any more problems.
Refrigerant LeakThe refrigerant in an air conditioning system is an essential fluid for absorbing heat and distributing it outside. If the coolant escapes the mini-split unit, you could be faced with a Refrigerant Loss. This usually happens when there’s a leak in the line or the refrigerant coils fail. When the refrigerant drops below what is necessary, the pressure gradient makes it hard for the mini-split to produce heat, leading to colder homes and decreased energy efficiency.Frost forming on either side of the evaporator can signify a Refrigerant Leakage.
Coil FreezingEvaporator coils in mini split systems freezing is a common issue. It’s caused by a lack of airflow or insufficient refrigerant charge. This leads to low pressure and below-freezing temperatures, blocking air flow and reducing heat transfer. Plus, the compressor can get damaged if not taken care of.To avoid this, make sure there’s plenty of air flow. Clean or replace filters as needed. Also, get a professional to inspect your refrigerant levels, and gas up or repair any leaks.Be careful if you attempt to fix the system yourself. It’s dangerous and may void any warranties. Always consult a certified professional.HVAC Insider explains that improper installation or maintenance of mini splits can cause freezing coils. 
Low Refrigerant ChargeLow refrigerant charge could be the culprit. Refrigerant helps transfer heat and keep your space comfortable. Inadequate charging during install, excessive use, faulty components. Low refrigerant can lead to poor performance, high energy costs, and costly repairs. Monitor the charge regularly to avoid issues.
Mini-Split Air Conditioner ClogMini-split air conditioners can experience blockage, which stops them from heating properly. This is due to the buildup of moisture and debris in filters or coils. So, it’s important to check filters and coils regularly, and replace them if needed. Plus, you should inspect the drainage line for blockages. Not maintaining this can lead to costly repairs or even full system replacement.To avoid clogging, it’s best to clean air filters, coils, and drain lines routinely. suggests that servicing your HVAC equipment can save up to 15% on energy costs.
Mini Split Repair NeedsThese issues can be serious, causing the air con system to break down completely. Keep it well maintained to avoid a breakdown during hot weather.Common repair needs include:Refrigerant leaks damaging the compressorBroken wires or control boards causing malfunction

What to Do if Your Mini-Split is Dripping Water?

If you spot water dripping from your mini-split, it could mean various issues. So, take these steps to rectify it.

  • Turn off the air con and unplug it.
  • Check the drain pan for any debris or algae buildup and clean it if need be.
  • Inspect the condensate line for blockages and use a wet-dry vacuum or a stiff wire to clear them.
  • If you notice ice formation on the evaporator coils, switch off the unit and let it defrost before restarting.
  • Also, adjust the angle of the mini-split so condensation doesn’t collect within the unit.
  • If nothing helps, contact a certified HVAC technician.

Condensate Drain Issue

The condensate drain can cause a malfunction in the mini-split system. Here is a 3-step guide to fix the issue:

  • Take out the debris from the pipe and clean with a mixture of water and vinegar.
  • Inspect the pipe for any bends or kinks that can lead to clogging. If there are any, try to straighten them out gently.
  • Lastly, check for leaks around the pipe joints and block them with waterproof silicone sealant if necessary.

Outdoor Unit Blocked

The mini split’s outside component may not work properly if something blocks its airflow. This can cause a lack of heating and affect temperature regulation. 

Debris, plants, or other physical obstructions around the outdoor unit could be the cause. So, it’s key to inspect and maintain the exterior regularly.

To fix this, one must get rid of anything near the outdoor unit that might limit airflow. Make sure there is 24 inches of clear space on all sides. If needed, hire a technician to examine and sort out any issues.

Improper Mini-Split System Level

If your Mini-Split System isn’t balanced, it can lead to inefficiency and wacky heating/cooling. But, fear not! You can level it correctly with these 4 steps:

  • Check the unit’s stability with a bubble level.
  • If it’s not level, use shims to stabilize it until it’s straight.
  • Securely tighten screws and bolts on both the indoor and outdoor units.
  • Re-check the levelness of the device with a bubble level and add more shims if needed.

Air Around Ductless Mini-Splits

Ductless mini-splits have a unique effect on the air around them. They generate heat, warming up the room and creating cool air nearby. This means the air temperature is constantly comfortable.

No ductwork is needed, so there’s less energy loss. Plus, adjustable airflow direction and speed make them even more efficient. 

Mini-splits also improve living conditions by eliminating allergens and microbes with their air purification system. Installation is easy, with minimal disruption.

These systems are eco-friendly, reducing energy use by 30-50% compared to traditional HVAC units. Studies show they save energy and improve air quality, making them a good alternative to regular heating and cooling systems.

Clogged Drain Line

  • Turn Off: Off the mini split and cut off power.
  • Remove Debris: Check for debris or mold blocking the drainage. Get rid of it.
  • Flush Drain: Use some water from a cup to flush out any remaining dirt.
  • Reconnect: Plug the mini split back in and turn on.


The common problems of the inefficiency to blow hot air from heat pump can be solved by taking proper measures and by consulting the technician.


What is a mini split?

A mini split is a type of heating and cooling system that does not require ductwork.

What is a heat pump?

A heat pump is a device that transfers heat from the air or ground to provide heating or cooling for a building.

Why is my mini split not heating?

There could be several reasons why your mini split is not heating, including insufficient refrigerant, a clogged air filter, or a problem with the indoor air handler.

How can I troubleshoot my mini split?

Check the air filter, make sure the thermostat is set correctly, and check for any visible damage or leaks in the system. If you are still having issues, it’s best to call a professional for assistance.

How can I diagnose the issue with my mini split not heating?

You can perform a few simple checks to diagnose the issue with your mini split not heating, including ensuring that the thermostat is set to the correct temperature, inspecting the air filter for dirt or debris, checking refrigerant levels, and examining the evaporator coil for frost or ice build-up.

Can a dirty air filter cause my mini split not to heat?

A dirty air filter can cause your mini split not to heat as it can restrict the airflow, which reduces the amount of heat that the unit produces.

How do I prevent my mini split from not heating in the future?

You can prevent your mini split from not heating in the future by regularly cleaning or replacing air filters, scheduling annual maintenance checks with a professional HVAC technician, ensuring that the refrigerant levels are proper, and preventing the evaporator coils from freezing by keeping the temperature above 60 degrees Fahrenheit.

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