Split unit problem.

[itstony]

It seems I like I have a compressor problem.

Lost R401 (never closed valves).
Vac´d and regassed after 6-months.
Seems like the comp isnt putting out.
All electrics kicking in ok, no flow of cold gas on the line.
Tried heat, starts to flow on hot line and slowly reached the heat exachanger inside, but eventually kicks out, so trips working.

Ant tips on what to check at the comp?
I did get a belt from the casing 6months ago, ground had come away in the house, so picked a leak to earth.
Not sure this is the cause, but hope it was and caused an easier fix than the Comp???

[james10]

You have more then a compressor problem. You need the A team for this one (or the local A/C Engineeer);)

[itstony]

if the local engineer could have dianosed the problem, I would not be asking for help on here.

[monkey spanners]

Is this a basic non inverter chinese unit?

Based on the info you have supplied i would be thinking shortage of refrigerant, again.
Would need recovering and weighing to see though...
And if its short would need the leak finding and fixing.

Also....

http://www.youtube.com/watch?v=_MVonyVSQoM

[itstony]

It´s a Mitsubishi SRK 25sd-s.

It was VAC´d down and refilled, but I wasn´t around.
In fact that was the third time it was filled and the same lack of cooling was evident!

I never knew you could collect the R410 from the unit, so stupid question, whats the best way?
It´s not cheap.

I can then weigh it myself when refilled.
I guess that will make sense to start from there. I still think its a comp prob.

[nike123]

I still think its a comp prob.

Or 4-way valve maybe.

[monkey spanners]

It´s a Mitsubishi SRK 25sd-s.

It was VAC´d down and refilled, but I wasn´t around.
In fact that was the third time it was filled and the same lack of cooling was evident!

I never knew you could collect the R410 from the unit, so stupid question, whats the best way?
It´s not cheap.

I can then weigh it myself when refilled.
I guess that will make sense to start from there. I still think its a comp prob.

You will need a recovery machine, a reciever bottle, gauges, a set of scales with 10g or better resolution, nitrogen bottle, regulator, hand tools, extension lead, ppe, new R410A, vacuum pump, vacuum gauge, shreader core depressors, know what you are doing, F gas ticket, amongst other things.

It will be easier and much cheaper to get an engineer out who knows the equipment and what they are doing. Maybe your local Mitsubishi importer could recommend a good company?

[itstony]

LOL, just a like a morning safety meeting on an oil instalation complex.
You made your point and no arguments.
But.
To find a person that will follow the HSE and Safety requirements as you state will be very, very difficult. Most come with a van and less tools and equipment than I have.
As for PPE, ony I use these things. In fact, I insist the basics are worn.

Primarily, I see no reason why an attempt to look and find an easy fault should not be encouraged.
Isn´t that the purpose of forums??
If it is in need of a specialist, then I accept it´s better to get one.
I think we all need to draw a line at what we are capable of taking on, after seeking help and guidance on trouble shooting.
Agreed or not?

[monkey spanners]

Primarily, I see no reason why an attempt to look and find an easy fault should not be encouraged.
Isn´t that the purpose of forums??
If it is in need of a specialist, then I accept it´s better to get one.
I think we all need to draw a line at what we are capable of taking on, after seeking help and guidance on trouble shooting.
Agreed or not?

I'm all for doing things yourself, i work on my van and lorry yet have no formal vehicle training, i ask some mechanic friends advice if i get stuck with something.

But something has changed recently in the refrigeration and air conditioning industry to make it illegal to work on the equipment without having first passed an assesment, it is something this industry has long needed.
I am sure that many enthusiastic ameteurs could do a better job than some of the so called engineers in the industry, judging by there work! But never the less i am reluctant to encourage people to break this law by giving them step by step instructions on how to do things.

Does the system display any fault codes when it stops working? This may point us in the right direction, also if this is an inverter unit then i suspect the compressor will not speed up if the system senses it is not cooling or heating much. Compressor problems are very rare in ac systems that are installed to the manufacturers recomendations. This is why i'm thinking refrigerant problem.

Jon :)

[Fri3Oil System]

In Spain regulations forbid to sell refrigerants to non authorised people and/or companies, by the R.D. de los gases fluorados (F-gases Regulation). So, even if you could DIY, you couldn't or should be allowed to buy refrigerant.

In Summary, you can't fix it yourself legally, sorry about it.

Regards,

Nando

[itstony]

Yes Jon, I fully understand your views and as a mech-engineer myself, I also have issues with non time served people in jobs they never did the time to get City and Guilds.

I do respect qulified personnel and we all know the larger majority are not.
I am not for buying a van, painting a sign on it and going commercial, that is wrong. Trying to trouble shoot my own equipment is in my book a must. Most times it´s simple, when not, call someone. But not for every single problem.

To give a better picture, I have had two so called specialists. Neither have refrigeration certificates. In fact, I doubt I could find one that does easily.
So, I am fed up and before I seek a Mitsubishi specialist, I just want to have a look and see if it´s something obvious.
I shall not get involved with the refrigerant side, but I have checked the electrics and board and as far as I can see, thats all fine.

How much R410A should have been added? I can then ask if he weighed it as I know he should have.
As you say, he may have short changed me and i did pay for the bottle also.

[monkey spanners]

The outdoor unit will have the factory charge size on a label with the model no. etc near the pipe connections, that will give you the basic charge that will do for a short pipe run, anything over that will have had a trim charge of 'x' grams per meter.
I doubt your system would hold more than 2kg and most likley nearer 1kg.
The only way to charge these is to recover the refrigerant and weigh more in, there may be another connection inside the unit as using only the ones on the valves where the pipework is connected may not get all the refrigerant out (and nitrogen after leak testing!) if the eev (refrigerant flow control) is in the shut position.

Jon

[itstony]

The outdoor unit will have the factory charge size on a label with the model no. etc near the pipe connections, that will give you the basic charge that will do for a short pipe run, anything over that will have had a trim charge of 'x' grams per meter.
I doubt your system would hold more than 2kg and most likley nearer 1kg.
The only way to charge these is to recover the refrigerant and weigh more in, there may be another connection inside the unit as using only the ones on the valves where the pipework is connected may not get all the refrigerant out (and nitrogen after leak testing!) if the eev (refrigerant flow control) is in the shut position.

Jon
Thanks Jon, I am going to open the cowling and just see if anything is obvious.
Does the 4-way valve go to a default setting for filling? Maybe that isn´t an issue whát position it´s in?.
I had this inkling about the valve a few weeks ago, but both
people that came never mentioned it.
I have no way of filling with N2, so if I come up against a blank, I shall do some searching for a reputable engineer...... God help me on that one:rolleyes:

[monkey spanners]

4 way valve is to switch between heating and cooling modes, eev regulates refrigerant flow to match load and compressor speed. System may have more than one eev or check valves etc.

4 way,

http://www.youtube.com/watch?v=6Wt-JJ3JpzE&feature=related

eev,

http://www.youtube.com/user/EmersonClimateTech#p/u/9/k_0WWoyB1wI

Just to get a rough idea on what they do.

Jon

[nike123]

If 4-way valve is not fully made trip from one position to another (some damage of valve or derbies which block his free movement to end positions), than compressor has bypass from discharge to suction, and have symptoms of faulty compressors. Then compressor overheats and eventualy trip on internal overload device.

[Gary]

It seems I like I have a compressor problem.

It is always a mistake to start a trouble shooting procedure with a wild guess at what might be wrong. It just misleads people. Remove the word "compressor" from the above sentence and you have a much more logical starting point.

First you need to confirm airflow through both the indoor and outdoor coils. We do this by measuring the entering and leaving air temperatures through each coil. Better yet, report all four temperatures in both cooling and heating modes.

[itstony]

Thanks guys, thanks for taking your time to respond.
I am really looking forward to check this unit out and now have a little more knowedge and basic understanding.
I doubt I shall tinker too much, but I will at least be able to trace the paths and see what´s going on.
Report back later, watch this space ......

[Gary]

It´s a Mitsubishi SRK 25sd-s


Are you sure it isn't SRK 25zd-s?

[itstony]

Are you sure it isn't SRK 25zd-s?

Yes that´s the kiddie!

Eyes are not what they used to be ;)

[Gary]

I'm thinking this might be helpful:

http://mitsubishiheavy.com.ua/docs/pdf/rac/SRK25_35_50_ZD-S.pdf

[itstony]

Thank you Sir!
I have saved that and will have a good read the weekend.
I love to learn these things and have an understanding.
Good man Gary

[itstony]

Gary,
That file was a very comprehensive manual indeed. I never knew the unit was so involved.
To be honest I got quite lost at the involvement of this unit. I then got involved on another project to let my head clear.
I did check the unit out and it will send hot fluid to the inside unit but it wont circulate as it should, fsr too slow. It makes a strange straining sound from the exchanger inside as though the fluid isnt flowing.
It then cuts out outside to cool down I assume.
When I switch to cold after a while, I can feel the cold gas at the same place inside at the copper pipes before the exchnager, but nowhere near as cols as it should be. After a few minutes it doesnt seem to be sending any more cold or cooled gas. No straining sounds on cold, only hot.

I inquired with the last so called engineer how much R410a he filled and told 0.9Kg. The connecting pipes are 50cm only.
I will have to try and locate a decent engineer, but after the last two I want to get some idea of what the problem is. I don´t have all the tools to tackle this alone.

[monkey spanners]

Pipe run is too short at 50cm...

[Gary]

I don´t have all the tools to tackle this alone.

You don't have a thermometer to check air in and air out temperatures?

If you can't handle a thermometer, then you shouldn't be tackling this at all.

[Makeit go Right]

Question, please: Could you give a little more information on this bit?

Lost R401 (never closed valves).
Vac´d and regassed after 6-months.

eg, Was this condenser separated from the system with valves left open (ie being repositioned/reused somewhere else) with the refrigerant lost when moving it? Just wondering if the above means that air was able to get inside, into the compressor gas/oil ways, for 6months.

[itstony]

Jon,
Half a metre is distance from outside unit to the inside, that is the standard length of the copper tails supplied without adding. Two others are the same and fine, so was this one before.

Gary,
I have stated I just want to find out the area of concern before I ask a "Third" so called engineer. I am tired of incompetent people twice now and would rather not keep calling people in hope one does know his stuff.
If the heat and cold is barely just getting to the exchanger and then stopping, a thermometer isnt going to help me or anyone else, my fingers were enough to tell me at this point. I have three of these and can tell from them clearly what temp the copper tubes should be reaching. This one is way, way nowhere near the others.

[itstony]

Question, please: Could you give a little more information on this bit?


eg, Was this condenser separated from the system with valves left open (ie being repositioned/reused somewhere else) with the refrigerant lost when moving it? Just wondering if the above means that air was able to get inside, into the compressor gas/oil ways, for 6months.

Yes, could have.

[monkey spanners]

Jon,
Half a metre is distance from outside unit to the inside, that is the standard length of the copper tails supplied without adding. Two others are the same and fine, so was this one before.



I don't doubt that is how they were installed, but every split system i have installed has had a minimum pipe length (usually around 3 meters) as well as a maximum.

If the pipe run is too short there is a risk that not all the refrigerant will have room to vapourise before it returns to the compressor, this can lead to liquid slugs in servere cases and oil dilution in milder cases, neither are conducive to long compressor life.

Jon

[Gary]

Jon,
Gary,
I have stated I just want to find out the area of concern before I ask a "Third" so called engineer. I am tired of incompetent people twice now and would rather not keep calling people in hope one does know his stuff.
If the heat and cold is barely just getting to the exchanger and then stopping, a thermometer isnt going to help me or anyone else, my fingers were enough to tell me at this point. I have three of these and can tell from them clearly what temp the copper tubes should be reaching. This one is way, way nowhere near the others.

How foolish of me to ask for air temperature measurements, when you are able to tell everything there is to know by simply wrapping your calibrated fingers around the pipes.

So... what do your magic fingers tell you? Do they tell you that you have no clue?

[itstony]

Well Gary, it is obvious you have gone from trying to be helpful to being somewhat disrespectful. I see no place where I have been disrespectful on any thread. Only distain shown was to those that came to my house to fix equipment they couldn´t, a job they were incompetent on and taking on daily in a commercial fashion.

I read the technical information you kindly sent and did take note of the method of measuring temp in and out of each unit. I did state earlier there was a cooling on the outside unit, but only a minute amount of cool gas barely able to get to the inside exchanger barely detaected by my fingers.
Do you never use your fingers to detect small changes in surface temperatures....ever?
On heat it reaching the inside unit on the pipes at the same point, but not getting throgh the exchanger quickly. If it was, I could have followed the method with a thermometer with someting to measure. It doesn´t get that far to do this.
With another unit in the next room, comparison is easy to follow and see it´s not working right.

Thanks for your help to now, sorry my efforts to obtain knowledge annoyed you. No apologies for wanting to ask and learn on an open forum. That´s what they are for.
I never wanted to tool up and be a refridgeration engineer in a day, only ask help to identify what the problem might be from you guys before I call yet another ´Specialist´and hope he actually knows what he is doing next time.

[itstony]

Question, please: Could you give a little more information on this bit?


eg, Was this condenser separated from the system with valves left open (ie being repositioned/reused somewhere else) with the refrigerant lost when moving it? Just wondering if the above means that air was able to get inside, into the compressor gas/oil ways, for 6months.

From the replies, this may be a cause. I may point this out to the next guy that comes.
Will he need to purge the whole system out with N2?

I have seen they just empty the unit twice. Last time only was it vac´d down and refilled but no change.
Seems like the pipework needs to be established its clear first before they do anything else.

[nike123]

I don't doubt that is how they were installed, but every split system i have installed has had a minimum pipe length (usually around 3 meters) as well as a maximum.


Jon

Monkey, that is not rule. There are some units with minimum length and there are also some without. In instalation manual of each unit is stated minimal length.

I personally fitted few thousands of split-systems of various make, and usually, only concern with minimum lengths are multi units and units of high power, like 5kW or more.

Example:http://i51.tinypic.com/2v2h20h.jpg

[nike123]

From the replies, this may be a cause. I may point this out to the next guy that comes.
Will he need to purge the whole system out with N2?

Not at this stage!!


I have seen they just empty the unit twice. Last time only was it vac´d down and refilled but no change.
Seems like the pipework needs to be established its clear first before they do anything else.You need systematic approach and not guesswork to diagnose fault. Therefore you need measurements with instruments and not your fingers. So, Gary is not disrespectful, he ask what is needed to diagnose problem without guessing.
If pipes are clogged and gas not circulating it will be clear from measurements.

Too many assumptions in this thread and not single measurement. This is how job should not be done.

Find competent service engineer recommended by Mitsubishi service since you are not having required tools and instruments to do anything except comparison of two units in work.

Yes we are using our senses to help in diagnosing problems but that is not enough to find fault in most cases. It is only indication. We need accurate measurements in temperature diferences and pressures end we will sort any problem eventualy.

[Gary]

I have taken on various projects outside my area of expertise and have at times asked for advice. If told to measure this or that, I measure this or that, because asking someone for advice and then not following his instructions would be... somewhat annoying... perhaps even disrespectful.

[Makeit go Right]

Was this condenser separated from the system with gas lost and valves left open for 6months when reusing/moving it....with air able to get inside, into the compressor gas/oil ways.
Yes, could have.

6months with air into the compressor ways....possible oxidisation inside, and the compressor oil filled with moisture from the air.:confused:
R410a-oil is very reluctant to give up its moisture once it has it.

If I were you, I'd take the cheap+easy route: throw the condenser and get a new one (don't waste any engineer-time/money trying to salvage it...too expensive/silly). Blast the FCU with nitrogen to get out any oil you can from inside walls of pipes (unless a new FCU comes in cheap, in which case throw the FCU too). Fit a drier in pipework to remove any remaining moisture etc in the FCU. And rerun new pipework so it's within perameters.

[itstony]

6months with air into the compressor ways....possible oxidisation inside, and the compressor oil filled with moisture from the air.:confused:
R410a-oil is very reluctant to give up its moisture once it has it.

If I were you, I'd take the cheap+easy route: throw the condenser and get a new one (don't waste any engineer-time/money trying to salvage it...too expensive/silly). Blast the FCU with nitrogen to get out any oil you can from inside walls of pipes (unless a new FCU comes in cheap, in which case throw the FCU too). Fit a drier in pipework to remove any remaining moisture etc in the FCU. And rerun new pipework so it's within perameters.

Thanks for the response.
I couldn´t be 100% sure if the valves were closed when the units were split. I think they were, but the pipes were reconnected within the hour.
I then waited for the guy to come for six months.
Sorry if I was not clear.

I am busy at the nmoment, but plan to check the outside unit temps front and rear as that did feel like it was getting quite cold on the back. I must confirm this next. Nothing getting indide though.
I hope it isnt as bad as you say.
Thanks again.

[Makeit go Right]

but the pipes were reconnected within the hour. I then waited for the guy to come for six months. Sorry if I was not clear.

Ah, that is not so bad, especially with the short run. Would need the drier and pipework rerun, though.

[momo]

Recovery may be possible IF the system was at least left adequately sealed albeit with some air/humidity in the pipe run. (To just blow out the air with R410 on filling is only a good practice at wrecking the system.) If it was later wholy emptied and vacummed: the only way to be sure is to suck out for hours AND heat with an electric heater all accesible parts including the compressor. I have done this for customers but you can see them visibly twitching at the thought of the bill for labout time!!! And they do not look convinced when you explain that "due to the loss of refrigerant air and water will have been sucked INTO the system...." and the consequences thereof.... On the ZDS range there is no place to put a normal drier without a bodge and one the liquid line would have to be a reversable one (debatable since it will also suffer when used as a heat pump). Having tried to locate a replacement outdoor ZDS unit in Spain for a customer recently: non were available or maybe they could not care less. PS You did not tell us what the trip out/fault codes were.

[stanleyzhao]

typical trouble of refrigerant-cycle split type domestic heat pumps. The indoor and outdoor units are connected by copper coils, which is easily be damaged. So refrigerant leakage is always a problem to this kind of products.

The solution is water-cycle type domestic heat pumps: no outside copper coils. Heating exchange is done in the unit. So there will be no leakage any longer. Wave heat pumps are good alternative.

[exotiic]

typical trouble of refrigerant-cycle split type domestic heat pumps. The indoor and outdoor units are connected by copper coils, which is easily be damaged. So refrigerant leakage is always a problem to this kind of products.

The solution is water-cycle type domestic heat pumps: no outside copper coils. Heating exchange is done in the unit. So there will be no leakage any longer. Wave heat pumps are good alternative.

What in the world are you talking about? How does this fit in with the relevant issue?