Mitsubishi mini split not blowing hot air

Many Mitsubishi mini-split users become concerned when their unit fails to provide cooling, often not realizing the issue until they find themselves in freezing conditions.

If your Mitsubishi mini split is not providing heat, and you're unsure of the reason, there are several possible explanations.

The lack of heating in your Mitsubishi mini split may be due to the heat mode not being active or the unit being undersized for the space it is intended to heat. Other potential causes include a tripped breaker, a blocked air filter, obstructions around the outdoor unit, incorrect temperature settings, a refrigerant leak, a frozen coil, or problems with the compressor or circuit board.

Given the variety of issues that could result in a non-heating mini-split, it is essential to consider all these factors if you plan to troubleshoot your air conditioning system.

To simplify the troubleshooting process, I will provide explanations and solutions for all ten possible causes. Additionally, we will delve into why your Mitsubishi mini split might struggle to provide heat in cold weather, why it can cool but not heat, and why the heat pump may fail to deliver heating.

Why Is My Mitsubishi Mini Split Not Heating?

1. The Heat Mode Might Not Have Taken Effect

Typically, there is a brief delay of a few minutes after activating the HEAT mode before it starts producing warmth. Therefore, if your mini split doesn't immediately begin heating, it doesn't necessarily signify a malfunction.

Solution: No action is required in this case, as it is not a malfunction. Simply be patient and wait for a few minutes for the mini-split to reach its desired heating temperature.

2. The Unit Could Be Undersized (Too Small for The Space)

If you haven't properly matched your space with the appropriate air conditioning system, your unit may not function effectively. If your AC unit is struggling to provide heat, one potential reason could be that it is undersized for the space it is meant to serve.

To address this issue, it is advisable to check the unit's BTU (British Thermal Units) rating and compare it to the manufacturer's recommended specifications for the space in which it is installed.

Solution: If you find that your mini split is too small for your space, consider upgrading to a larger air conditioning system with a higher BTU rating that matches the size of your area. This will ensure more efficient heating and cooling performance.

3. The Circuit Breaker Could Be Tripped

Before considering costly repairs, it's essential to inspect your circuit box for any tripped circuit breakers. Keep in mind that a tripped breaker can interrupt the power supply to your system, making it difficult for the HEAT mode to function as intended.

Solution: If you find that a circuit breaker is in the "off" or "tripped" position, simply reset it by turning it back to the "on" position. This should restore power to your mini-split and potentially resolve the heating issue.

4. The Air Filter Could Be Dirt Clogged

While many of us commonly associate a clogged filter with issues related to cooling in a mini-split, it can also be a culprit for a unit that isn't providing heat.

The challenge with a dirty, clogged air filter is that it hampers the unit's airflow, and when airflow is restricted, the air conditioner struggles to produce heat.

Solution: To address this problem, examine the air filter for signs of dirt and clogging. If the filter is disposable and filled with dirt, replace it with a new one. If the filter is designed to be reusable, remove it and wash it thoroughly to remove accumulated dirt and debris. This should help restore proper airflow and improve the heating performance of your mini-split.

5. The Outdoor Unit Could Be Blocked

The outdoor unit of your mini split system contains critical components such as the compressor, condenser, electrical parts, and a fan. Because it is constantly exposed to weather elements like rain, wind, and snow, regular maintenance is essential to protect it.

This maintenance helps prevent the accumulation of debris, dirt, branches, and other contaminants that can obstruct the unit. When the outdoor unit becomes blocked, it is unable to operate efficiently, impacting its ability to provide cooling and heating.

Solution: To address this issue, inspect the outdoor unit for dirt, debris, and any other forms of contamination, and clean it thoroughly. Additionally, it's important to maintain the area around the outdoor unit to minimize the amount of dirt and debris that can accumulate in the first place. This will help ensure the optimal performance of your mini-split system.

6. The Temperature Mode Could Be Wrong

If the temperature set on your mini split is lower than the current room temperature, the air conditioning system will not provide heat. Additionally, selecting the incorrect temperature mode can prevent the mini-split from heating.

Ideally, the unit should generate heat when the 'Heat Mode' is activated. When in 'AUTO Mode,' the unit will automatically heat or cool depending on the room's temperature. However, if you choose 'Dry' or 'Cool Mode,' the mini split will not provide heating but will instead cool the space.

Solution: To resolve this issue, ensure that the unit is set to 'Heat Mode' if you desire heating, or select 'AUTO Mode' to enable the AC to adjust automatically based on temperature changes. If you manually adjust the temperature setting, make sure it is set higher than the current room temperature to activate heating.

7. The Refrigerant Could Be Leaking

A low refrigerant level can impact not only the cooling but also the heating function of mini splits. It's important to remember that refrigerant is responsible for absorbing and releasing heat in the room. However, this process is disrupted if there's a refrigerant leak, which can occur due to poor installation or damage to the unit.

Solution: Dealing with a refrigerant leak is typically not a DIY task and should be handled by a professional technician. Before contacting an expert, you can check for signs of a refrigerant leak, such as dampness and unusual odours around the air conditioning system. If you observe these signs, it's advisable to seek professional assistance to diagnose and repair the issue correctly.

Pros and Cons of Mitsubishi Mini-split

Pros

• Operational Status Indicator
• Temperature Adjustment
• Diagnostic Aid

Cons

• Louvre/Fan Issue
• Potential Confusion
• Limited Error Information

Differences Between Mitsubishi Mini Split and Mitsubishi Electric Air Conditioner

Mitsubishi Mini-Split

Mini-split systems consist of two main components—an indoor unit and an outdoor unit. They are connected by refrigerant lines and require a relatively simple installation process. Mini-splits are known for their flexibility and can be installed in various locations within a building.

Mitsubishi Electric Air Conditioner

Traditional air conditioners are typically centralized systems that consist of a single indoor unit connected to a ductwork system. Installation is more complex, involving ductwork design and installation, making them less flexible in terms of placement.

Alternative to Mitsubishi mini split

Daikin

Daikin is a well-known brand in the HVAC industry and offers a wide range of ductless mini-split systems known for their energy efficiency and reliability. They provide various models suitable for both residential and commercial applications.

Mitsubishi Mini Split Not Heating in Cold Weather

In many instances, your mini split may struggle to provide heat in cold weather due to the accumulation of ice, which can overwhelm the monitor fan and coils. To address this issue, it's advisable to take the following precautions:

1. Cover the outdoor unit: Protect your outdoor unit from ice buildup by installing a cover above it. It's important to note that the cover should not obstruct the unit's sides, as this can interfere with airflow. The cover should be positioned above the unit.
2. Raise the outdoor unit: While covering the outdoor unit can shield it from falling snow, it may not protect it from snow accumulation on the ground. Therefore, it's a good practice to elevate the unit to prevent ground snow from causing issues.
3. Turn on the defrost setting: Another effective measure is to activate the defrost setting on your mini-split system. This setting helps prevent ice buildup and freezing of the condenser coils, improving the unit's heating performance in cold conditions.

Mitsubishi Mini Split Cooling but Not Heating

If your Mitsubishi mini split is providing cooling but not heating, the primary reasons for this issue could be one of the following:

1. Ice buildup: In colder weather, ice can accumulate on the unit, blocking the fan motor and covering the coils. This ice buildup hinders the mini-split's ability to produce heat effectively.
2. Wrong temperature mode: If you have set the mini split to 'COOL' mode instead of 'HEAT' mode, it will cool the space rather than provide heat.
3. Dirty coils or a filter: Filthy or dusty evaporator or condenser coils, as well as a clogged air filter, can cause the unit to briefly cool but fail to produce heat.
4. Tripped breaker: It's essential to check your circuit breaker box, as a tripped breaker can interrupt power to the mini split. If you find a tripped breaker, reset it to restore power to the unit.

Identifying and addressing these potential issues can help resolve the problem of your mini split providing cooling but not heating.

Mitsubishi Mini Split Heat Pump Not Heating

Your Mitsubishi mini split heat pump might not provide warmth immediately because it takes a few minutes for the HEAT mode to become fully operational.

Another possibility is that heating is hindered by factors such as obstructed air vents, icy coils, lack of outdoor maintenance, or a tripped circuit breaker. Therefore, it's important to investigate all these potential issues to identify the specific reason your heat pump is not heating as expected.

Conclusion

When faced with the issue of a Mitsubishi mini split not blowing hot air, it's crucial to consider a range of factors.

Whether it's the delayed activation of the HEAT mode, obstructed air vents, frosty coils, outdoor unit maintenance, or a tripped breaker, addressing these issues promptly can help restore the efficient heating performance of your mini split system.

Regular maintenance and attention to these potential problems will ensure your Mitsubishi mini split continues to provide reliable heating when you need it most.