LG mini split: one indoor unit won't turn on

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  #1  
Old 03-12-15, 09:19 PM
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LG mini split: one indoor unit won't turn on

I have an LG dual-zone mini-split heat pump in a two-room addition to the house. It's worked fine for the last two years.

But now one of the zones will not turn on. The other room (and therefore the condenser) works fine.

The remote has good batteries and it indicates that the unit should be on. Nothing changed (except having to restore clock and settings) after using the reset button on the remote.

The power icon is just flashing twice, then a pause, then flashing twice, repeating. If you attempt to turn it on via the remote or the button on the face of the unit, it will beep, but will not turn on; just keeps flashing twice.

The user manual is useless of course, and just says that if it won't turn on, check the power. Well, it's powered from the outside machine, so that's not the problem.

This is Model LMN090HE.
 
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Old 03-13-15, 12:22 PM
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According to the manual on that unit, 2 flashes indicate "Indoor In-Piping Error". I'm not sure how much help this is, but that's what the error code indicates.
 
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Old 03-13-15, 01:54 PM
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An LG with an issue? (Sarcasm). Your not alone with your LG system. Don't even know what to tell you to look for. Might be time for a tech to put some gauges on it.
 
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Old 03-13-15, 02:07 PM
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According to the service manual it's not piping error.... it's pipe sensor error. You'll need an ohmmeter to check its resistance as well as the operating voltage of the circuit it's connected to.

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Old 03-15-15, 06:13 PM
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Well, I got 5kOhm on the sensor and only a couple hundred mVDC. I guess that means it's the board. Thanks for the testing procedure. I'll call LG on Monday, I guess. Can I expect that two years is still under warranty? I know it would be for central air conditioners.
 
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Old 03-19-15, 03:04 PM
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Well, maybe that was premature. The new board didn't fix it, and while the board was out, I found more "sensors" to test. None of them have plugs that look like that picture. The two I tested today, one on piping with gray wires, one in front of discharge with black wires, are connected at the same 4-wire plug on the board. The discharge was at 9.5 kOhms, and the other was at 3.3 kOhms. Is that far enough away from 5 kOhms to be the issue? The supplied test procedure said to expect 0 or infinity when it fails.
 
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Old 03-19-15, 11:42 PM
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What I posted above came directly from the service manual. Try downloading a copy here....
PDF manual for LG Air Conditioner LMN090HE

There are three sensors.... indoor air sensor, inlet pipe sensor and outlet pipe sensor. So you needed to check the one on the refrigerant line coming into the unit....hence the inlet pipe sensor.

The inlet pipe should be the smaller one of the two connecting tubes.
 

Last edited by PJmax; 03-20-15 at 12:03 AM.
  #8  
Old 07-12-15, 02:25 AM
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LG air conditioner LMN090HE

My LG air conditioner won't turn on also. I came home from work and turned it on it was working fine, I fell asleep on the couch and woke up to the unit off and it will not turn on. I have two indoor units and neither of them will come on, the remote works fine but will not turn on the units and neither will the on/off switch on the units themselves. Can anyone tell me why it would turn on and work then just shut itself off and not come back on and what I can do to fix it?
 
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Old 07-12-15, 10:35 AM
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Welcome to the forums.

There could be a dozen reasons why your A/C won't turn back on.

I left a link to the service manual previously. Download it and start on page 65 where it lists troubleshooting and service codes.
 
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