Ductless minisplit not giving hot or cold air

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Old 11-24-15, 11:14 AM
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Ductless minisplit not giving hot or cold air

Hi,

I installed Mitsubishi minisplit early this past summer. I ran the copper lines 65 feet--less than the maximum recommended for this unit (100ft) but more than the 30--which means that I had to call a company in and charge the line for me.

All went well. It worked great all summer long.

But, near the end of the summer, I stopped getting cold air. It still blew air, just not cold--like a fan.

The first thing I did was realize that I had not cleaned the air filter, which is on top of the air handler. It was filthy. I cleaned it and then the unit blew cold air again.

But, a couple of weeks later, it stopped blowing cold air again. I have also tried it on the heat setting and get no hot air. The air blown is the same regardless of if I have it on a/c or heat.

I would suspect the freon is low, but the fact that cleaning the air filter gave me cold air again (even if only for a week or two) seems strange.

Any ideas on this?
 
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Old 11-26-15, 06:25 PM
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I assume when the unit stops blow cold/hot air, the outside unit is also stopped. If it is, you need to find out why. there may be some cut off switches in the outside unit, you will need a multi-meter and also know how the system works before you can work on the problem yourself. Every mini-split unit is designed differently. The quick way to fix this problem is call Mitsubishi tech support and see if they can help you.
 
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Old 11-26-15, 06:28 PM
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On a Mitsubishi split there should be diagnostic LED's to aid in troubleshooting.
Posting the model number of the system will help us to help you better.
 
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Old 11-26-15, 09:29 PM
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The inside unit is:
Mitsubishi MSeries HyperHeating 18000 BTU Mini Split Indoor Unit Wall Mounted Heat Pump - MSZ-FE18NA

The outside unit is:
Mitsubishi MSeries HyperHeating 18000 BTU Mini Split Outdoor Condenser Heat Pump - MUZ-FE18NA

I'm pretty sure the outside unit is on. It is so quiet it is hard to tell.

To check the diagnostics, is that under the cover of the outside unit?

I'm generally pretty handy but these manuals are REALLY confusing to me.
 
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Old 11-26-15, 10:10 PM
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Download the manual. Start on page 17. That would be section 10 where it says Troubleshooting and follow the steps they provide.

The one LED is on the inside unit control board.

If you're not technically/electronically inclined you may want to call for service. These are not easy units to service.

Mitsubishi pro/media/214712/muz-fe09-18na_service_obh543a_9-10.pdf
 
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Old 11-29-15, 08:39 AM
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Well, I used the troubleshooting from the remote control which should tell me what is wrong based on blinking patterns.

There are no strange blinking patterns at all.

So, I guess there is no problem with either indoor or outdoor unit--which leaves me with low freon as the problem.

Unless I did something wrong.

It just still seems strange that it worked fine for a couple of weeks after I cleaned the air filter.
 
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