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Mitsubishi Air Conditioner Troubleshooting and Repair

Since the introduction of mini split ductless air conditioning one of the leaders has been Mitsubishi. There are now many of these units in service. Even though these Air Conditioners are extremely reliable, there are problems with them from time to time.
When these problems arise you need to know where to go to get online manuals and troubleshooting guides.

As a professional the place that I go is to the Mitsubishi website: www.mrslim.com
Here you can find a ton of information for the homeowner as well as for the professional.
The nice part about this site is that you do not need a password to get into the professional side of this site. I there are all of the resources that the professionals use, and they are available to everyone.

If you want to shortcut right to these resources just go here:

From the drops down menu you can access all of the manuals that are available for any model. Then you can have full access to troubleshooting guides. They are simple and easy to understand. Many issues can be figured out and fixed by a handy homeowner.

Take the time to cruise around and look at all of the materials includes in this site, there are many things that will give you tons of great information about the Mitsubishi line of air conditioners and heat pumps.

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no power at interior unit. power everywhere else

If this is a mini split ductless there is a control wire with 3-4 wires inside (normally red, white, blue and green) that is connected from the outdoor unit to the indoor unit. This wire feeds voltage from the o.d. unit to the I.d. unit. If all connections at the o.d. unit are good, then check for voltage at these connections at the o.d. unit. If no power at these connections then a circuit board has faulted. Call a tech. and have a tech support number ready (1-800#) in case your service tech don't have it.

May 12, 2015 | Sanyo KHS0971 9,000 BTU Ductless...

1 Answer

panasonic mini split air conditioner css9nkua error code h99 what does it mean

12.11 Freeze Prevention Control 2
• Control start conditions
o During Cooling operation and soft dry operation ? During thermo OFF condition, indoor intake temperature is less than 50°F or ? Compressor stops for freeze prevention control
o Either one of the conditions above occurs 5 times in 60 minutes. • Control contents
o Operation stops
o Timer LED blinks and "H99" indicated
You may need the assistance of a technician. Service manual located here:

Apr 29, 2015 | Panasonic CS-S9NKUA Ductless Mini Split...

2 Answers

I am not able to get the unit to change from air conditioning to heat

Unfortunately these units are not user fixable , beyond checking for power and checking battery in remote. You would need to call a pro who is able to get service information and has special digital logic meters to diagnose and repair .

Oct 04, 2014 | Mitsubishi MXZ-2B20NA-1 Mr. Slim Dual Zone...

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