Mitsubishi Mini Split Not Heating

A Mitsubishi Mini Split system is known for its energy efficiency and reliable performance in both heating and cooling modes. However, if you find that your Mitsubishi Mini Split is not heating as it should, there could be several reasons for this issue. In this guide, we will explore common causes and solutions for a Mitsubishi Mini Split system not heating properly.

1. Thermostat Settings


Inspect and Replace the Air Filter: A clogged or dirty air filter can restrict airflow, reducing the system’s efficiency. It’s essential to inspect and replace the air filter regularly. A dirty filter can also cause the unit to freeze up, hindering its ability to heat effectively.

3. Power Supply

Verify the Power Supply: Ensure that the unit is receiving power. Check the circuit breaker and the power supply switch. Sometimes, a tripped circuit breaker or a turned-off switch can lead to heating issues.

4. Remote Control Batteries

Check Remote Control Batteries: If your Mitsubishi Mini Split is controlled via a remote, low or dead batteries can prevent proper operation. Replace the batteries and ensure that the remote control is functioning correctly.

5. Outdoor Unit

Inspect the Outdoor Unit: Examine the outdoor unit to ensure it is free from obstructions such as debris, snow, or ice. Any blockage can affect the unit’s ability to extract heat from the outside air.

6. Mode and Fan Settings

Check Mode and Fan Settings: Ensure that the unit is set to the appropriate heating mode (e.g., heat pump or electric heating) and that the fan is set to the desired speed. Adjust these settings as needed.

7. Refrigerant Levels

Assess Refrigerant Levels: Low refrigerant levels can result in poor heating performance. If you suspect a refrigerant leak, it’s crucial to contact a qualified HVAC technician to diagnose and repair the issue.

8. Fault Codes

Review Error Codes: Mitsubishi Mini Split systems often have self-diagnostic capabilities that display error codes. Refer to the user manual to decode any error messages. These codes can provide valuable information about the problem.

9. Regular Maintenance

Perform Regular Maintenance: To prevent heating issues and ensure the long-term efficiency of your Mitsubishi Mini Split, it’s essential to schedule regular maintenance by a professional HVAC technician. They can clean coils, check refrigerant levels, and perform other critical tasks to keep your system running smoothly.

10. Technical Support

Contact Mitsubishi Customer Support: If you have tried the above steps and your Mitsubishi Mini Split still isn’t heating correctly, it’s advisable to contact Mitsubishi’s customer support or a licensed HVAC technician. They can provide further guidance and arrange for a professional inspection and repair if necessary.

Common Causes

No.CauseDescriptionTroubleshooting StepsRecommended Action
1Dirty Air FiltersClogged filters can restrict airflow and reduce heating.1. Check and clean/replace filters.Regularly clean or replace filters.
2Refrigerant IssuesLow refrigerant levels can affect heating capacity.1. Inspect for leaks.Contact a technician for repair.
3Thermostat SettingsIncorrect thermostat settings can prevent heating.1. Verify temperature settings.Adjust settings to desired temperature.
4Electrical ProblemsFaulty electrical connections can disrupt heating.1. Check for loose wires.Call an electrician for repairs.
5Blocked Outdoor UnitObstructions can hinder heat exchange in the outdoor unit.1. Clear debris around the unit.Ensure good airflow around the unit.


No.SymptomDescriptionPossible CausesRecommended Action
1Cold Air BlowingThe unit is blowing cold air instead of warm.Low refrigerant, thermostat settingCheck and address the cause.
2Insufficient HeatingThe room doesn’t reach the desired temperature.Clogged filters, thermostat settingTroubleshoot and fix accordingly.
3Unusual SoundsStrange noises coming from the mini-split.Fan or motor issues, debrisInvestigate and repair as needed.
4Frequent CyclingThe unit turns on and off frequently.Thermostat, electrical problemsCheck thermostat and connections.
5Ice BuildupIce forms on the indoor or outdoor unit.Refrigerant issues, airflow issuesAddress the root cause of icing.

Troubleshooting Steps

1Check Air FiltersEnsure filters are clean and not clogged.
2Inspect Thermostat SettingsVerify that the thermostat is set to heat mode.
3Examine Outdoor UnitClear any obstructions around the outdoor unit.
4Check for Refrigerant LeaksInspect for refrigerant leaks and repair them.
5Examine Electrical ConnectionsCheck all electrical connections for faults.

Professional Assistance

1Refrigerant Refill/Leak RepairLow refrigerant levels or leaks require a technician.
2Electrical RepairsFaulty wiring or connections should be handled by a pro.
3Complex Mechanical IssuesIf the problem is beyond basic troubleshooting.
4Warranty CoverageEnsure the unit is within warranty for cost savings.
5Routine MaintenanceRegular servicing can prevent heating problems.

Preventive Measures

1Regular Filter MaintenanceClean or replace air filters as recommended.
2Annual Professional CheckupSchedule an annual maintenance check by a technician.
3Keep Outdoor Unit ClearMaintain clearance around the outdoor unit.
4Proper Thermostat UsageUse the thermostat efficiently to avoid unnecessary heating.
5Educate UsersInform users about proper operation and maintenance.


In conclusion, a Mitsubishi Mini Split system not heating properly can be caused by various factors, ranging from simple issues like thermostat settings and dirty filters to more complex problems like refrigerant leaks. Regular maintenance and proper care can help prevent many of these issues, but when problems arise, it’s crucial to address them promptly to ensure your system’s continued efficiency and comfort in both heating and cooling modes.

Mitsubishi Mini Split Not Heating

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