Mitsubishi Electric Mini-Split not performing well

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  #1  
Old 08-31-19, 02:44 PM
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Mitsubishi Electric Mini-Split not performing well

I live in an apartment that installed Mitsubishi Electric mini-splits about two years ago (sometime in 2017)

The models are MSZ-FH12NA (Indoor unit) & MUZ-FH12NA (Outdoor unit)

The unit worked fine last year (I only use it for cooling although I did try it the heating function twice, I don't like it for heating so I use the baseboard heaters, which were already there).

Anyway I am in Fairfield County in the state of CT so the hot weather is almost over.

I have the unit set to 62F and the room is still 70F the air coming out of the unit is only 57F (measured with an infrared thermometer) the cooling coils (I took the filter out and the unit is in cool mode not the auto change over mode) are about 52F (Measured with the same thermometer)

The fan is on Turbo mode (The highest speed) and there is still a very slight layer of ice on the cooling coils so I am thinking the unit is somehow in the process of losing in refrigerant charge (R410A)

The apartment is also very humid right now the outdoor humidity is 47% and the indoor is 46% at night the humidity level in the apartment can reach 70-80% even with the AC on

The apartment is only 330 SQFT but there is a half wall where the bedroom area is (No door in my specific unit although some do have a door). and there is a small kitchen area in the front room area along with the living room.

I have already put a work order in on Thursday August 29th but they took the whole long weekend off (No surprise with the staff here).

Anyway sorry for the long read I am just wondering what I should tell them when they get here as the room will get down to about 68F at night but with high humidity.

I already had them here once and he said it is working fine as it putting out cool (but not cold) air.

I wish they could be here at night when the unit is blowing 65F air with the room temp about 72F but they leave a 4PM

I clean the two filters once a week so I have done all that is required of me. Anything other then that they are supposed to do all of the other maintenance of the units.

I obviously do not want to be footing the bill for an HVAC tech as that is what I think is going to be needed here

Again sorry for the long post
 
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Old 08-31-19, 04:17 PM
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Hi, you measured the supply air temp, measure the air temp where the air is going through the filter, report back with your findings.
Geo
 
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Old 08-31-19, 04:20 PM
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I am not sure I understand what you mean the indoor unit is mounted near the ceiling and the filters curve upward where I believe the unit pulls in the air from the ceiling. Do you mean measure the temp of the air the unit is pulling in?

I attached a picture that I took last year (Yes the filters are now clean)
 
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Old 08-31-19, 04:57 PM
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That’s an abnormally low setpoint to have your unit on.
The charge will likely need pulled and weighted.
 
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Old 08-31-19, 05:27 PM
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Exclamation

I know the lowest setpoint is 61F I used to be able to have it set at 66F and the house was comfortable but now I am miserable with the high humidity in the apartment the room is now 69.1F (51% Humidity) and the outside temp is 70.2 (57% humidity)

They are going to have to call an HVAC technician then as the maintenance staff are jack of all trades and master of none

I just don't want to get blamed for "breaking" the unit when I did nothing of the sort. I would of continued to use my window shaker but those are banned as they installed these "wonderful" state of the art Heat-Pumps.

I should really think of moving but with the low rent and the normal going rate I cannot afford anything else So I will just have to live with it
 
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Old 09-01-19, 04:43 AM
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Hi, measure the air temp going back into the unit near the ceiling, and where the discharge air is blowing into the space.
Geo
 
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Old 09-02-19, 04:00 PM
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The air above the unit is at about 68F with the unit blowing 64F air right now
The indoor temp is 70.2F with 49% humidity and the outdoor temp is 71.2F with 92% humidity.

Needless to say I am miserable in my apartment.

I think the problem is getting worse as I think this has been going on all summer as my apartment only got down to around 74F on the hottest days this year. I was somewhat comfortable but now with the lower outside temps and high humidity the problem is at it's worse

Also at night it seems like the compressor just shuts down as the unit starts blowing hot humid air like a humidifier and the humidity in the apartment goes up quickly
 
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Old 09-03-19, 12:48 PM
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OK the apartment maintenance staff just left a little while ago and he also thinks the unit is not working correctly (I thought it would be a fight to get them to admit that)

Anyway they placed a call to an HVAC tech and I will let the forum know what happens when they fix it
 
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Old 09-04-19, 05:15 PM
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Exclamation

OK Encon came once (to get a feel of what was wrong) said they would return so I asked the lady that took the work order when they would be back and now they are saying it works because it blows cool (Not cold like it used to) air. Time to get my family involved (One is a lawyer and will get them to fix it). I will continue to keep the forum posted (Unless this is not allowed)
 
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Old 09-05-19, 07:05 AM
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Hi, definitely not working right, only 4* temperature difference, should be around 10-15*, I believe.
Geo
 
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Old 09-22-19, 06:28 AM
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Smile

OK the AC is finally fixed! It was fixed on 09/19/2019 and they sent a different company as the first company refused to service it.

Anyway the unit was very dirty inside and the condensate drain was clogged. The refrigerant charge was fine and the unit is now working properly.

I guess the unit had a sensor or something so the drain pan would not overflow back into the wall or drip down the front of the unit.
 
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