Mitsubishi MUZ-FH12NAH evaporator doesn't get cold
So installed a MUZ-FH12NAH mini split.
It cools/heats slightly above ambient (ambient 25C, AC produces 20C in cooling, 30C in heating).
No leak or contamination 100%. Pressure tested to 250psi vacuumed down to 30 microns, holds the pressure and under 500 microns overnight.
The liquid line gets frosty (charge is 100% correct, 2.5lbs) , the evaporator doesn't get cold.
What can I do to diagnose this?
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how long is your lineset and have you triple checked your wiring is accurate?
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Check the valve on the mixed-phase ("liquid") line. It shouldn't be frosty, just wet with condensation when it's working. Something's restricted, the valve is the simplest answer.
After that, check the EEV. Make sure the coil is snapped down tight & plugged in. Maybe check the coil windings for continuity. Mitsubishi makes a magnet that'll drop over the EEV & allow you to manually stroke it. Once I found one that was sticking, I managed to free it up with the magnet.
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The liquid (thinner) valve is definitely fully open, counterclockwise to the left until it stopped. That line is frosty all the way to the evaporator.
Is the EEV inside the condenser? Is that the same thing as LEV?
Apparently there is one inside the evaporator too.
One thing i did wrong was breaking the vacuum with 100psi, that could have damaged something, you're supposed to use ~2-5psi to break vacuum.
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About 8 feet. Wiring looks correct
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Ice like that is charge or EEV issue.
is this a new install?Contact tech support and get it filed.
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New install, condenser (open box), evaporator (brand new).
Original r410a recovered, well vacuumed, new charge added by weight.
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you still need to recover and weigh the charge.
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not sure what you mean, as i said that was done already, exact charge is inside, no leaks to contaminants in the system.
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tech support will want to know how much charge is in there.
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2lbs 9oz as per the label, line set is short, no need for more.
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when you contact Tech Support they’re gonna ask you did you pull and weigh the charge.
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where did you purchase this?
Who installed it?
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THis unit didnt have refrigerant in it?
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It did but it was low. All refrigerant was removed, exact amount was added, since there is no way to just top up and be 100% sure the correct amount is in there and to also rule out contamination.
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you weren’t concerned when the indoor unit was low from the factory?
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sure, i couldn't return in.
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Yeah sorry, LEV == EEV, I misremembered the nomenclature.
Open box, were there signs that it had been installed once? Could be a return because it didn't work. IDK where you got it from, but the (please don't be offended) big box stores around here are well know to reshelve returns until the returnee marks all over the box with a sharpie "BAD DON'T BUY".
That mixed phase line is definitely waaaay too cold. The LEV stuck closed is the next simplest answer along with the LEV not opening due to mechanical or electrical issues.
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Could be anything, you're right, but it looked new, and the matching evaporator was completely new/sealed.
I'm reading the actual magnetic coil on the LEV sometimes gets unsnapped, i drove this this for 2 hours without the original box. A long shot but worth checking.
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Nothing wrong with the AC, EEV coil popped off during transport. They should zip tie them or something. Ice cold now. Thanks for the help guys!
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The coil on the LEV might not be seated correctly, the coil might be bad (winding shorted or open), the harness might not be seated correctly, the outputs on the board might be blown (there's a thread here somewhere where that happened, but it was due to a failed coil IIRC), the computer might have lost its mind & is not energizing the windings in the right sequence (exceedingly remote possibility).
Could be something else entirely, too. You said this is a heat pump, perhaps the reversing valve is sticking, but IIRC you said it does heat and cool, so it must be mostly shifting.
Take the side off & look at the frost. You should be able to follow that all the way back to the restriction. If it just stops in the middle of a pipe, or at a joint between two pipes, there's something stuck there. If it leads to a valve, whap it gently to see if it'll free it up.
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The AC works now!
The black part hanging is the coil, it's supposed to sit on the shiny cylinder with the metal clip snapped into the copper pipe. It got bumped off during transport i imagine. As soon as i snapped it back in place the AC began working as it should.
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Awesome, glad you got it working!
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sorry but the start up sequence is
EEV Command closed. Feed back is sent to the computer verifying this has happened.
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