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a man controlling the temperature on his mini-split with a remote

How to Reset a Mitsubishi Air Conditioner

a man adjusting the temperature of his mini-split with a remote

Source: antoniodiaz/

Mitsubishi mini split air conditioners are top-of-the-line heating and cooling systems, but they sometimes need to be reset to return to regular functionality. If your Mitsubishi air conditioner has stopped working, try resetting the system before calling a technician for help. Resetting a Mitsubishi air conditioner is easy, and it can solve numerous issues, from system communication errors to power issues after a power outage.

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When to Reset Your Mitsubishi AC

There are a few scenarios where resetting your Mitsubishi ductless AC system can restore it to its proper functioning. For instance, resetting your AC after a power outage can help, but if the cause of the malfunction is a dirty filter, resetting is unlikely to help. Check out these malfunctions that may be fixed with a quick reset.

After a power outage

When inclement weather causes a power outage, it’s possible it also caused a power surge. A power surge occurs when too much electricity is supplied to your home and appliances. Fortunately, AC units are usually connected to electricity through a breaker board or isolator that protects appliances from electrical surges. Breaker boards and isolators monitor electrical flow and cut off power if they register an unsafe amount of electricity. 

After a power surge or outage, check the AC unit’s breaker or isolator. If they are flipped, that means they are in a neutral position, and no power is being sent to your Mitsubishi system. Resetting your breaker or isolator should restore it to regular functioning.

Error code E6 (6840)

If your system has stopped functioning and displays the error code E6 (6840), resetting it may solve the problem. Error code E6 means a communication error between the indoor and outdoor units. A signal receiving error triggers when the indoor circuit board goes three to six minutes without receiving a signal from the outdoor unit. 

a technician testing an ac unit

Source: Andrey_Popov/

Error code E9 (6841)

The error code E9 (6841) is another communication error code, but it is a transmitting error. It triggers when the unit controller board fails to find a transmission path for three minutes. There could be physical causes for an E9 or E6 code like a short circuit or miswiring that restarting will not fix. Before contacting a Mitsubishi AC technician, reset your system because restarting sometimes solves a defective fan motor and circuit boards.

How to Reset Your Mitsubishi Air Conditioner

Once you determine that your system is not working properly, you should try to reset it using the remote control. All Mitsubishi systems from the Mitsubishi 6000 BTU mini split to the 42,000 BTU mini split have at least one wireless remote control. These remote controls have a reset button at the bottom under the panel. Pressing the reset button ensures the remote is working correctly.

an indoor open breaker panel

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If you believe the system is not working because its associated breaker is flipped, then you’ll need to find your home’s breaker board and reset the breaker assigned to the AC. Before you do anything, make sure the system is turned off. Once you find the correct breaker, switch it to the off position and wait 30 seconds. The 30-second wait lets the residual power in the system dissipate. 

Turn the breaker back to the on position and turn on the system with your remote control. It may take a few minutes for the system to become functional again. If it never returns to normal operations, then the problem requires a technician’s expertise.  

Your outdoor unit may have its own isolator, which functions the same as the breaker board. It is a switch next to the outdoor unit. Follow the same instructions as for the breaker. Turn off the system, switch the isolator to off, wait 30 seconds, switch the isolator back on, wait a couple of minutes, and turn the whole system back on.

When Resetting Doesn’t Work

If you reset your system and it continues to malfunction, you may need to contact a technician for repairs. Before you do, check the system’s air filters and the outdoor unit. Your system could be malfunctioning because of a clogged air filter. HVAC systems like the Mitsubishi 9000 BTU mini split have washable air filters, so you can easily solve a clogged air filter issue. 

The outdoor unit may be mechanically functional but rendered inoperable by clutter surrounding it. Outdoor units require open access to air, so if grass, clutter, or debris blocks the intake, your ductless AC fails to provide cooling or heating. Declutter and clean the area around the outdoor unit to prevent mechanical malfunctions.

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Use Mitsubishi’s and ComfortUp’s Great Warranty

If you have tried resetting and there are no obvious fixes for your system, it’s time to contact the manufacturer and get a technician’s help. Mitsubishi and ComfortUp offer great warranty deals with their ductless mini splits. With general knowledge about resetting your system and a great warranty, you’ll never go long without the comfort that your Mitsubishi mini split provides.

At ComfortUp, we carry products from multiple industry leaders, including Mitsubishi, GREE, and Boreal. Contact us today for more information about our products, and read our blogs to learn more about mini split technology.


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