problem with split a/c

[slothslag]

thanks guys for your info on pipe flareing.

I have a prob with a split a/c. there is no cooling or heating happening inside. when in cooling, the liquid pipe outside and where it connects to the outside unit gets very frosty. when in heating the gas pipe gets very hot , but nothing happeing inside.
Have I lost gas? Does that mean Ive lost oil aswell?

(im a sparky, but im learning) thanks

paul

[chemi-cool]

hi paul,

gas is missing and maybe a little oil.

find the leak, (usually ,the frair cups) top it up, make sure not tto much, and there you go.

in second thought, check that cup tube is not blocked,

you can do it by adding gas and see if suction temp. got higher.

good luck.

chemi

[frank]

Also, is the indoor coil fan operating? you can get the same effects as a shortage of gas if you are only looking at the pipes

[Jasper]

[find the leak, (usually ,the frair cups) top it up, make sure not tto much, and there you go.]


DON'T JUST TOP UP

1, reclaim
2, repair
3, evacuate
4, re-charge with refrigerant

[chemi-cool]

of course you right jasper.

I took it for granted that these steps are known and practiced.

chemi

[slothslag]

Thanks Chemi and Jasper.

I followed all these steps with the help of a friend who is an air con mechanic. Everything is fine now, however Im alittle worried that it might be slightly undercharged. When we were adding gas, we ran out to the point that we had to heat up his bottle to get alittle more out of it.

It is showing SLIGHT symptoms like it was before. We made sure there is no leak now. I was thinking that maybe i could get some more gas and a set of gauges and put alittle more in. How do I know how much? is it bad if i put too much in?

Any thoughts guys?



Paul

[Jasper]

which gas is it running on

[Jasper]

what is the make and model of the unit.
what is the pipe run length (one way)

[slothslag]

Hi Jasper,

Its a Daikin Inverter 2.5 Hp split
R22
and pipe length is about 4m 1 way. Basically a back to back installation.

Also I was wondering is there a way I can check how much is on there now just buy using a set of gauges?

Cheers

Paul

[frank]

On a Daikin Inverter split you must charge by weight only the amount stated on the unit. The factory charge is good for 30m of pipework. You CANNOT charge any other way as you do not know how loaded or unloaded the compressor is when charging. You certainly can't charge to a back pressure reading, or an amp draw.

Is it R407C or R410a?

[slothslag]

Hi Frank,

Its R22.

Your right that I dont know how much refrigerant is in there at the moment. Is there an easy way to find out how much? That way I can just put the gas bottle on the scales and charge the rest. If not, would it be feasable to release all the gas and that way I know there is nothing in there and then charge the specified amount?

what would happen if i put too much in?

[Bones]

reclaim into an empty bottle...

then weigh that back into the system, stopping when you reach the correct weight. Adding gas from another bottle of 22 if you require more gas for the correct charge weight.

(doing this of after knowing you have fixed any leaks etc on the unit first of course)

not familliar with daikin splits personaly, but would think the charge would be around 4kg give or take, it sound be on the plaque on the outdoor unit, along with model and serial numbers, amp draws etc (also most possibly indoor head).

do you know the exact charge frank off the top of your head?

[slothslag]

Hi Bones,

1.8Kg of R22. It says on the outdoor unit.

Can u tell me what the proceedure is for emptying all the gas into the bottle?

[Jasper]

Frank
He says it's on R22

[Bones]

Can u tell me what the proceedure is for emptying all the gas into the bottle?

do you have a fridge mate who would have a recovery unit? if he does, use this to suck the gas out of the system and into a recovery bottle. (perhaps he might do it for you if offer to quelch his thirst with beers hehe)

otherwise chill your recovery bottle, put it in a bucket with some ice or depending on the size put it in (there) your freezer for a little bit, as refrigerant will migrate to the coldest spot... thus hooking your guages to outdoor unit, purging to chilled recovery bottle will suck alot of gas out by itself.

also make sure you use a clean bottle and vaccuate it before recovering.

i take it your possibly not from nsw, otherwise have a fridge mate buying the 22 for you? if you are, dont get caught big $$$ fines.

[frank]

Daikin did not make any split units on R22 with inverter drives except for the vrv stuff. If you do not know how to reclaim refrigerant - what are you doing working on the equipment??

I don't want to sound condesending but it is a skilled job and should be left to the experts - not only as we have trained for a number of years but it can lead to severe accidents. enough said.

If you wish to post the model number of the outdoor unit I will gladly post the correct charge weight. There is no short cut to knowing how much refrigerant is in the system. You must reclaim the charge and weigh it (specialist equipment required). You must then ensure that the system is leak free and recharge to the manufacturers stated charge. If the system does not then perform as it should do, you have to start looking for the cause of the problem. Just by charging the correct amount of gas does not mean that it will work correctly.

GET PROFFESIONAL ADVICE.

[Peter_1]

Hi Bones,

1.8Kg of R22. It says on the outdoor unit.

Can u tell me what the proceedure is for emptying all the gas into the bottle?

Connect a half-full bottle to the thickest of the 2 tubes and start the compressor and turn the bottle then upside down.
As soon as you hear that the compressor stops and Amps are rising very fast - can take some time - then it's OK. Then all the gas is gone

[Brian_UK]

Connect a bottle to the thickest of the 2 tubes and start the compressor and turn the bottle upside down.
As soon as you hear that the compressor stops, then it's OK.

I'll go along with that Peter, it is after all the best way for fools to carry on and when the motor does stop it can be confirmed that the compressor is full.

[baker]

Daikin did not make any split units on R22 with inverter drives except for the vrv stuff. If you do not know how to reclaim refrigerant - what are you doing working on the equipment??

GET PROFFESIONAL ADVICE.

This is the problem with a worldwide forum. What applies to one country doesn't to another. In Australia, Daikin inverter splits are predominately R22, although R410A units are now becoming available. These are standard domestic splits. I have 2 in my house.

[iceman007]

Paul,
I have to agree with Frank. If you aren't totally 100% cetain leave it to a trained engineer (I don't want to sound condescending either, but it's so easy to make the problem a whole lot worse). We work almost exclusively on VRV systems and Hitachi VRF's. The Daikin VRV 2 is the 410A Inverter driven system.
The thing to do would be to reclaim the refrigerant into an appropriate vessel(you can't release the gas into the air) (liquid first if possible), and then get the remaining vapour out. Leak test using OFN- if you can leave it in overnight, and then once the leak is repaired, or the whole system is 100% pressure tight, pull a vacuum (to around 200 microns), and leave the system for a little while, making sure the vacuum holds (if the presure rises then stops, it's usually moisture in the system boiling off- so pull the vacuum down again until it holds). As the other guys have already said, check the manufacturers charge weight, and then WEIGH IN the correct charge. This way you can get the correct charge in. If you put in too much, then you can damage the compressor, as it will start to take in liquid slugs. The pressures will be high, and you still will not get the desired cooling, so it is essential that the corrct charge is weighed in. Hope this helps.

Regards

James

[slothslag]

thank you all for help. much appreciated.

especially iceman007 - thanks for your info

[slothslag]

hi guys,

if i fit gauges to the high pressure and low pressure sides. can i tell from that if it has correct charge, or at least near the correct charge or that im not going to ruin the compressor if ive put in too much? if so what values of pressure am i looking for and when?


Paul

[Peter_1]

hi guys,

if i fit gauges to the high pressure and low pressure sides. can i tell from that if it has correct charge, or at least near the correct charge or that im not going to ruin the compressor if ive put in too much? if so what values of pressure am i looking for and when?


Paul

Sure, you can. You must charge till you see HP is going up.
Almost same procedure as emptying the system as you asked in a previous post.
You must connect your gauges and your gas cilinder. You charge your system until you see the HP rising until you have a difference of +/- 50 K with ambient temperature.
You measure aslo the AMP's of the compressor and as soon you reach max AMP stated on the compressor, then it's correct filled.
If needed, adjust safety tripper on the current safety switch.
Don't bother if suction is becoming wet or iced. That's normal.
Suction pressure should be +/- the same as the suction pressure which corresponds to the temperature of the room (for 40°F, you need a suction pressure of 120 psig with R22.
Let me know if it worked.

[rbartlett]

i would hesitate to say that a frosting suction is 'okay' on a daikin split..to me it indicates (all else normal) it's overcharged..

although japanese condensers are oversized for europe so they will over condense and give a low suction -40 to 50 psig- they can ice during colder times if a 'split' is put into a comms room without hp control etc..

it's interesting that a lot of split a/c guys have absolutely no idea at what high pressure a split runs now a days..nor why it runs at 45 psi suction...

personally i feel the best way -aside from doing correctly- is to charge till it sweats at the suction flare nut -if it frosts i take a little out

bit like charging to the frostline on fridges etc

cheers

richard

[chemi-cool]

hi paul,

a good operating split, depends alot on a good installation. some times, a lazy installer would bend a pipe by hand, almost stoping the gas flow. in such cases, you can charge it forever and it will not show you proper suction/discharge temps.

check by hand all the bends to eliminate this problem.

as peter said, check amps. on every split you will have a lable that show the working conditions, it is usualy different amps in cooling or heating modes, so make shure if what you measure is ok.

in most modern splits, condenser fan is controled be condensing temp.( on/off)
does this one have that control? is it working ok?
do not forget that in heating mode, condenser becomes evaporator and if the fan stops, suction temp will drop.

on a split that works in cooling mode in the winter or cold ambient you must install head presure control, these little devisces sense the condenser temp and control the fan speed. very useful in computer rooms for example.

go slow arround all the possible reasons for your problem.

I think that all the suggestions you got her, have to cover the problem.

please, let us know what was it.

good luck
chemi

[iceman007]

Paul

You can connect gauges and charge to the correct level. The easiest way is to look at the label and weigh in the correct charge. If you cannot do this then you may need to charge by superheat, if it's a normal split with no inverter.

Connect the low and high side gauges to the ports and connect the service hose to the bottle. If its a non azeotrope YOU MUST TAKE THE REFRIGERANT FROM THE BOTTLE AS A LIQUID (if its R407c or R410a charge as a liquid - if there's only one port on the bottle you will have to turn it upside down to draw liquid). Only open the valve on the gauges approximately quarter of a turn to let the liquid flash off in the lines before the compressor draws it in. Take a temperature measurement on the suction pipe at the condenser and watch carefully the LP reading on the gauge. Charge a little at a time and let the system settle down each time rather than bomb charging it in. Take the temperature scale on the gauge and compare to the temperature reading on the suction pipe and charge slowly until the temperature of the pipe is approximately 5 to 8 degrees higher than the temperature that the needle on the compound gauge is pointing to. This means that the superheat is approx 5 to 8 degrees, and the compressor will not be drawing in liquid, but the evaporator will be performing as it should. In any event you should also feel the air off the condenser start to warm up as it rejects the inside heat. If you connect the HP gauge, once the system has settled, look at the needle and read off the temperature indicated for the gas in use. This temperature should typically be 20 degrees C (35 deg F) higher than the ambient temp- if the system is condensing too much over this than there could be a problem. Once you have done that, make sure you check that the compressors current draw is within the range shown on the plate.#
Most important of all, before you do any of that, make sure it's pressure tight and correctly evacuated.
Hope this helps out- any problems send me an e-mail.

Cheers
James

[slothslag]

hi guys,

thanks for the info. The system IS an inverter but this is some data that i have got from it.

i put it in cooling on powerful mode. it was a mild day outside. about 25 deg C

rated current is 11A on cooling but it was sitting on about 8A fairly steady the whole time in powerful mode.

temp of suction pipe = 6.4 deg C
temp of liquid pipe = 14.8 deg C

suction pressure = 60 psig (corresponds to -4 deg C on gauge)
liquid pressure = 100 psig (corresponds to 12 deg C on gauge)

indoor unit air on = 22.6 deg C
air off = 6.4 deg C

outdoor unit air on = 25.4 deg C
air off = 31 deg C

everything was fairly steady the whole time. does this sound like everything is okay? I am alittle concerned about the liquid line pressure. is it too low?


cheers


Paul

[rbartlett]

you are probably not reading discharge pressure -if their is a connector on the smaller 3/8 pipe service valve then you were reading the 'pre expansion'pressure -if so 100 is about right..

cheers

richard

[slothslag]

what is pre expansion pressure? i had the high pressure gauge on the liquid line service port it is a 3/8 " pipe

[iceman007]

hi guys,


temp of suction pipe = 6.4 deg C
temp of liquid pipe = 14.8 deg C

suction pressure = 60 psig (corresponds to -4 deg C on gauge)
liquid pressure = 100 psig (corresponds to 12 deg C on gauge)

indoor unit air on = 22.6 deg C
air off = 6.4 deg C

outdoor unit air on = 25.4 deg C
air off = 31 deg C

everything was fairly steady the whole time. does this sound like everything is okay? I am alittle concerned about the liquid line pressure. is it too low?

It's difficult to charge an inverter system by measuring amps, as you won't be able to measure the compressor loading accurately. If it's a Daikin unit then i think you must measure in the correct charge. It's difficult to be able to fault find from the other side of the world, but I think that the LP is a little low if the liquid is evaporating at -4 degrees (make sure the indoor coil doesn't ice up). I would be looking for a temp just over zero. The outside air is around 25 degrees, then the HP should show the system to be condensing at around 45 degrees, and you should get sub cooling of between 4 and 7 degees. If you are on R22 the values I would look for (in theory) would be, a suction pressure of around 60 psi-gives evaporation temp of around 2 degrees, and a suction line temp of between 7 and 10 degrees (5-8 degrees superheat), HP of around 240 psi (at 100 psi it will not condense as the condensing temp MUST be higher than ambient) 240 psi shows a condensing temp of about 45 degrees, and the sub cooling should be ideally 4-7 degrees, gives a liquid temp out of the condenser of between 38 and 41 degrees.

What you have is a slightly raised superheat and not correct sub cooling (could be lack of charge), but the suction pressure seems OK (if it's R22), but from what you have said, are you on R407C?

This is only theoretical summary, and in practice could be different, let me know how you get on

James

[rbartlett]

the expansion device on most splits is in the condensing unit.
therefore you are reading a liq/gas pressure after that device

hence you are not reading discharge pressure

in order to do this some -but not all- have another schraeder in the discharge pipe out of the compressor but before the 4 way valve....
look for a fitting in amoungst the pipework above the compressor...

if you manage to fit your gauges on this one you would read a much higher pressure 220 -270 psig

cheers


richard

[slothslag]

no its r22.

now i am confused. am i measureing the condenser pressure or "pre evaporating pressure" on the service port of the small pipe?

where is the tev? is it in the indoor unit or the outdoor?

and if what you say is right about 45 deg C condenser temp why is the small pipe about 15 deg C and not 45 deg C?

thanks

Paul

[Peter_1]

i would hesitate to say that a frosting suction is 'okay' on a daikin split..to me it indicates (all else normal) it's overcharged..

cheers

richard

Haven't seen the

Sorry, but I think Paul better calls an aircotech because his questions are so elementary that I think he never worked on an airco before.

Same for

no its r22.

now i am confused. am i measureing the condenser pressure or "pre evaporating pressure" on the service port of the small pipe?
where is the tev? is it in the indoor unit or the outdoor?
and if what you say is right about 45 deg C condenser temp why is the small pipe about 15 deg C and not 45 deg C?

TEV?
Pre-evaporating pressure? 100 x

Perhaps the last discovered 'inverted pre-subcooling' of the liquid at ambients of 20°C?
You see what I mean.

[rbartlett]

if you read my post above it answers all your questions..

cheers

richard

[slothslag]

okay thanks richard ill check it out

[slothslag]

richard ,
there is no port where i can fit a gauge between the compressor and the reversing valve. is there any way of checking the condensing pressure now?

[slothslag]

peter 1 ,

mate i am doing all this to learn. i will not "call the pro" because oneday i will be the pro, how do i get there?? ... by asking elementary questions

[rbartlett]

any chance of getting a digital camera and posting a couple of pics?

and a model/serial number..

cheers

richard

[Peter_1]

Wasn't the filter completely clogged whereby in cooling mode there was no load on th evaporator and in heating mode it became very hot, so no sufficient cooling of then the condenser?
Fan was running but Frank already asked this?
Just a completely clogged filter. Have a look or run without filter for some time or open the simply the suction grille and let it run. Same symptoms?

[chemi-cool]

hi marc,

I would like to add that when the filter is clogged with dirt for some time, the dirt is getting inside pass the coil and lands on the wings of the tangential fan.

the result is almost no air coming out because the the curve of the wing is now straight.

chemi

[chemi-cool]

thank you marc for the lesson.

it amazing how every day I learn something new.

chemi

[iceman007]

no its r22.

now i am confused. am i measureing the condenser pressure or "pre evaporating pressure" on the service port of the small pipe?

where is the tev? is it in the indoor unit or the outdoor?

and if what you say is right about 45 deg C condenser temp why is the small pipe about 15 deg C and not 45 deg C?

thanks

Paul

Paul
The HP gauge will show the pressure measured at the condenser outlet. Look at the corresponding temperature. That is the temp at which condensation will take place in the condenser. It must be about 20 degrees or so higher than the ambient temp, because if it isn't heat cannot be effectively given up from the vapour in order to condense back to liquid. The TEV is usually in the outdoor unit, but some manufacturers have them inside as well (I think maybe Toshiba is an example).
The temperature of the small pipe has nothing to do with the condensing temperature (well it does but don't want to confuse things) The difference between the condensing temperature measured on the gauge (HP) and the temperature of the small pipe is the subcooling. The temperature of the small pipe should be less, and this tells you that liquid is leaving the condenser- in other words it's working because for the system to work properly you must have liquid at the TEV inlet. You can check the discharge line temp out of the compressor and see what it is-it will be much warmer than the small pipe out of the condenser if the condenser is working properly(if you did have a problem with the condenser the HP is usually high)

Any problems you can contact me.

Happy Easter to you all !!

James

[Peter_1]

The pressure and temperature of the small tube measured at the service valve on the outside of the unit - including Toshiba, Daikin, Mitsubishi, ... - is mostly not subcooled liquid.

The real HP pressure should be measured - as Richard explained - can only be measured at a service point before the 4 way valve or at that connection where you should connect the additional fan speed regulator.
IF it's fitted.

In most machines, the expansion - and again, for the smaller units mostly not a TEV but a capillary tube - is fitted in the outside unit.

Capillary tubes are used because they're less expensive then a TEV.

So the small tube is liquid at LP - or some sort of intermediate pressure and mostly relative very cold.

Reason why both lines have to be insulated, even in a only cooling unit.

Reason why they fit it (expansion device) in the outside unit is - according to Daikin - because this give less noise in the inside unit. The hissing or sissing (what's the bloody English word for it ?) is then only be heard in the outside unit and the indoor unit is much quieter.

[slothslag]

ahh!!
thank you everyone for your info and advice

everythign is sorted now and i have learned so much.

i set free the charge of gas and weighed in a new charge 1.8 kg is what it said on the name plate. i made sure there was a tiny bit of pressure in there before i recharged to make sure air didnt enter the system. i used my mother in laws kithen scales. I ballanced the gas bottle upside down on ones side with about 3 house bricks on the other. then i put exactly 1.8kg on with the gas and charged till it ballanced again.

having said all that i never found out how much was in there. we suspect it was too much, but then again, it could have been too little. but anyway everything is working perfectly and the same as an identical a/c unit i have.

im suprised how technical it is to try and confirm the amount of charge in these inverter splits. it seems like complete guess work with just a set of gauges and a thermometer. i suppose the fact that its an inverter and has a mind of its own doesnt help.

now i look forward to my next a/c or refrigeration challenge

i know im a naughty ******* for polutng the atmosphere. this was just a one off

[iceman007]

Paul

You really should not be working on this equipment, as you obviously do not have the correct equipment to undertake the work. In the UK for intentionally releasing gas to the atmosphere the penalties if caught are severe. Upto 5 years in prison and/or an unlimited fine. It is a very serious matter and whilst not wishing to sound condescending, you just cannot vent gas out. If you don't have the equipment to recover the gas properly, then leave it to someone who has.

If it's only a reasonably smallish unit then Peter is correct it will have a capillary in the outdoor unit, and the only way to measure the condensing pressure is at the outlet from the compressor. In any event pressure/temp relationships only hold true wheb there is a mixture of vapour and liquid whereas leaving the compressor you would usually only have superheated vapour.

I apologise for sounding blunt but please get the correct equipment.

(Peter, hissing would probably be a good bloody english word for it) I can't speak Flemish but a little Dutch- I can't remember the Dutch for it- I think sisklank ?.

regards
James

PS Learn something every day don't you.

[chemi-cool]

hi james.

thats what happens when you try to help, the guy didnt have a clue what he was doing, we gave him all the practical information, and now you are getting mad because he wasnt doing it right.

in this field, if one doesnt know the theoretical side of the matter or in other words, did not study it properly, he sould not touch it.

he could kill himself in other situations.
I think we have to find a way not to develope "cowboys"

dont ou think
chemi

[Peter_1]

Hello Iceman,

Dutch is in fact the same as Flemish.
I'm living in the Dutch speaking part of Belgium and the call us Flemish.
The 2nd part speaks French and called Wallon.
There is also a small (soem cities) German speaking part, the German kanton.
It's indeed sisklank in Dutch. Where did you learnt this?

I didn't want to be rude to Paul but what he need is someone from who he can learn the job, straight the correct way without the trial and error method.

What was now the real cause of his problem? Air in the system?
Released also the air with the gas?
He will never know it and has in fact not correctly repaired his machine.
'We will try this and see what happens. If it dont work, we will try something else, perhaps this will help then'.
With this technique, I even can repair a Rolls Royce Trent jet engine.

But any way, he's one who wants to learn the job, a dying rase. And not ashamed to ask questions/advices.

Did you know we installed systems of Daikin 50 kW with a capillary tube, delivered by Daikin?
As far as I know , all commmercials splits have cap tubes, even the big ones.

[Brian_UK]

i know im a naughty ******* for poluting the atmosphere. this was just a one off

Yeah, your "one off" added to the next persons "one off" ends up with your children and childrens children suffering.

A little more responsibility is required if you want to proceed with this line of work.

[Abe]

I have followed this thread through its entirety and it has been intresting to see the reactions of the various members.

On the one hand, we have a member wanting to learn something, asking questions, in a simple format.

On the other we have knowleageable members who in a patronising manner wish to belittle and berate the member or members.

The question I ask, Everytime anyone asks something, Is one in fear of being admonished for ill practice, ignorance or lack of technical knowledge and practice?

Does one look over the shoulder each time or refrain from asking anything lest it be construed as elementary and worthy of contempt.

[Brian_UK]

I think there is a difference between those who wish to learn for a valid reason, self education, work progression etc. and those who are trying to do something on the cheap.

I do not mean cheap as in cash terms but attempting a repair, install, modification of a piece of equipment that they know very little about in the hope that all will be well.

Yes I know that there are different standards across the world as to what we do with refrigerants but if I went to someones house and decided to empty their LPG storage cylinder into the house through a fitting in the kitchen would that be acceptable? or if I didn't know the capacity of a cold water storage tank in the roof space should I just dump the contents over the room underneath before refilling it?

It is difficult to be objective at all times when performing distance learning as we do here sometimes especially when you are unaware of the capabilities of the person at the other end of the forum. How would we all feel if this person had, in fact, lost two or three fingers due to severe frostbite when he dumped his system refrigerant charge and we hadn't provided sufficient warnings etc?