Finally Mini-split!

I'm sure many of you have seen my many many threads on that Mitsubishi Electric Mini-Split?

#1

#2

#3

Well they finally got it fixed!

Well I have only been complaining for what two years!!!!

Anyway back in August it was not doing much of anything (other then wasting electricity that I pay for)

So they sent a real tech and as I was saying all along it was low on refrigerant (R-410A) it had practically nothing in there! The fittings (all 4) were only hand tightened so it leaked out!

Anyway is checking the pressure the proper way to charge it? As that is all the tech did the older dial gauges and a pink container of R-410A. At the time the outside was around 83° F as soon as he put it in the air started getting a lot colder even colder then when it was installed by the idiots in mid 2017!

I thought they also had to go by Sub-cool and Super-heat and other measurements of then pressures?

 

Reading your list of posts it seems as though your idea in #1 may have worked?
I won't be going into charging a system to much other than saying analog gauges, a temperature probe, and the ability to add/subtract will give the figures you mentioned. Digitals are more convenient as they do the math for you. I wouldn't judge a tech by what they are comfortable using vs what you perceive to be improper. Judge them instead on their results. There is at least one other way to properly do the job relying on primarily an even different piece of equipment.
Hope you system continues to perform properly for you. If it did leak out, without help, then you probably still have a leak.

 

Well he used analog "Yellow Jacket" gauges it had to be running when he did it (I know this as I have done the vehicle AC's before with R-12 and then R-134A no not at the same time different cars) and he did it by pressure only it went to high and he let it equalize as he put it by letting a bit out,

Well it is working fine even better then when it was put in!

I think it leaked out as the fittings were never tightened only barely threaded on by hand!

He said this is the 4th one he fixed with the same issue. 186 apartments and he did 4 already!

I don't care if it continues to work beyond the Summer of 2022 as I'm leaving this dump of a place soon anyway for this and many other issues!

 

Minis must be charged via weight. Not pressure.

 

And a scale was the "different piece of equipment" I was referring to. I didn't know if that would be jumping into an area to be avoided.

 

How is this done with a scale and math?
What about any that did not go AWOL how is that calculated in the weight added not asking step by step just what is needed?


Edit:

I don't care if the tech was correct all I care about as it works (for now) He also tightened all 4 fittings. The indoor was a PITA and a Half to get to as well!

 

All manufacturers have a formula for additional refrigerant to add per extra foot of lineset length. They come precharged, that weight is listed on the outdoor unit.

 

Not sure the lineset is about 10 - 15' give or take a few feet that I can't see

Well on the cooler days it is doing the same thing as it did before but I think it may be doing what it is supposed to as it can't go down to 1BTU so it just shuts off the compressor until the room gets warmer?

I don't know he just connected a green jug to the low side (Looked like a green propane tank) and stopped when it started getting cold and the pressures were within what he said was OK?

 

Improper charging procedure. That’s likely why it’s still not working correctly.
There is no “correct operating pressure” on an inverter drive mini.

 

I thought so as the compressor is not on/off like the old ones but can ramp up down AKA VRF or variable refrigerant flow so the pressures are different depending on how power it is on.

Is there an easy way to make it stay on all of the time? as in unplug a sensor (or that would probably make it error out and do nothing?)

Anyway I looked up "green refrigerant jug" and that is R-22 but this is an R-410A unit and why would they waste the good stuff on something that does not need R-22?

There is a sensor in front of the indoor heat exchanger that can be unplugged easily do you know what that is for?

they call them heat exchangers (at-least that what Mitsubishi Electric calls them in the service manual) now as it can be the evaporator or condenser depending on what mode it is in.

 

Green is R-22.
Pink is R-410A.
Sounds like the guy needs a class or two on how to service units.
There are certain charging procedures. But no way to charge by pressure even if it’s running flat out.

 

Why would he use the good stuff as R-22 as it is already in short supply?
He did say "This would make it way colder then it ever was"


Is there an easy and reversible way to get it to just run 100% percent and ignore the thermostat?

I can be my own thermostat if it gets too cold I can just turn it off for a bit

 

He used the wrong refrigerant. It’s not that R-22 is “the good stuff”.
The oil in that compressor isn’t even comparable with R-22. The guy appears to have no clue what he’s doing.
Thermostat is needed. You can’t lock the thing on. That’s not how it works.

 

Maybe it was reclaimed R-410A?
R-22 is the good stuff it is cold in a properly working system same with R-12. Also does not operate at such high pressures as R-410A does

I know it does not work like this but is there anyway to make it work like this?

I'm jellious of the people who's portable or window AC had the compressor relay get stuck/welded on!

 

Did you put the R-22 in the unit?
Different refrigerants are different entities. One isn’t better then another. And they are not cross compatible. R-410A runs at the pressures it does because of its chemical makeup and operating parameters.
Same with R-12. It isn’t a cross replacement for R-22.
P/T chart isn’t even close. Wrong refrigerant will kill the unit.

 

Any updates? Does it actually have R-22 in it?

 

No the guy used a green jug

No it has R-410A as they only paid for that and not the high R-22 price.

It has R-410A but apparently not enough as it still cuts off on low pressure switch activation on cooler days but outdoor temps below 55° I can just open the door with a fan on to keep comfortable but the 70° > when I really need it it works fine.

 

Is this the bottle that was used? Nothing green at all about R-410A. Reclaim bottles are gray and yellow. Low charge can also kill the unit. With poor compressor cooling and low oil return.

 

Yes,
I asked for clarification I called the guy (Not housing) he said had 2 containers in the cart he brought the green R-22 was for the older 10 years old (Dry shipped AKA no refrigerant inside at all) 2.5T AC in the office he had his van in the other area he only bought over a cart on wheels. He actually hooked the pink R-410A jug, I was not paying attention totally just thought I saw him hook up the green one.

R-410A is not green (very high global warming Potential) anyway more of a "stop-gap" for the new flammable stuff that is being used now such as R-600A R-290 R-32 R-1234YF and probably more now.

I still think it is a tad low someone told me years ago to put a blanket or towel over the back outdoor unit (Condenser in cool mode I used it in heat mode once I'll stick to my $ baseboard heaters) to raise the refrigerant pressure as the condenser stays hotter or something like this as they do this for charging in cooler weather known as a condenser blanket.

Will doing something like this long term (EX: not charging in cold weather) hurt it? I'm obviously not going to do this on hot summer days.

 

R-410A bottles are pink.
You can’t charge via pressure. He didn’t charge it right, and now it still doesn’t work before he didn’t charge it right.
No, the blanket idea will not work.
Since he found it low on refrigerant, where did he find the leak and has he fixed it yet?

 

He claimed the fittings were loose they were a bit. I tried telling him to check what looks like an oily substance in the indoor unit but he claimed it was just mold and another company is going to clean it. anyway they washed it and that stain is not mold (it came back) it is hard to see but it looks to be on the bends where the copper tubes connect to the fins a lot of rust is present now! What a POS this is!

Anyone still make a decent window AC? That is what I'm going to do this summer as I'm tired of this issue.
I'm going to buy one now as I can get one cheaper then the summer rush prices.


Edit: If I buy one now can I safely test inside as long as the inside temp is not too cold for it to operate properly?