Help Re Window AC

[kssoin]

I have a window ac 19000BTU.
The max motor amps 9.4A
Refrigerant R 22
The gas had leaked from the twin capilaries.
The evaporator fins had corrofed so I bought another one. This one had more surface area and the tubes are having a bigger ID I was told the inside has a spral.
The compressor is a rotary compressor make ? because the sticker on the compressor does not dive the name of the manufacturer.
I removed all the oil(as much as possible) from the compressor by tilting it. It was abt 100 ml.
The gas charge of 995 gms is stated on the compressor label. I have no clue as to the oil.
I looked up data sheet of copeland compressor of same cap it had an oil charge of 1100 ml.
How do i determine the oil quantity. I vacuumed about 1100 ml of oil into the comp.
The liquid line out of the condenser is 3/8" od pipe to which is cononnected a drier filter that has a fine mesh in it. One end accepts the 3/8" pipe and there is exit for two capilaries at the other end.
I replaced the old capilary with a new one with same ID and length.
One thing is strange, the caps open into abt 2 feet of 1/4"OD pipes. The other end of these 1/4" pipes is connected into the evaporator.
I charged the gas and adjusted the charge by reaching the max compressor current.

The compressor made funny sounds. I surmised thd the oil quantity was more so I flashed the R22 refrigerantinto the refrigerant bottle. Let it settle down and recharge only vapour (upright bottle).
This was repeated a number of time till the compressore stopped making funny noises.
After two three days of running the max com current has come down to 8.5 amps down from 9.4 amps.

I will make arrangements to measure temp of liguid out from condenser and vapor into the compressor and post them.
BTW the min temp achieved is 23 Deg C.
How do I tweek the system to get more cooling?
At time of charging the disch pressure was 235 psig and at suction it was 65 psig.
This is the first time i have under taken this work.
Regards

[taz24]

I have a window ac 19000BTU.
The max motor amps 9.4A
Refrigerant R 22
How do I tweek the system to get more cooling?
At time of charging the disch pressure was 235 psig and at suction it was 65 psig.
This is the first time i have under taken this work.
Regards

Hello

2 things spring to mind.

Firstly you took out 100 m of oil but put in about 1100m of oil.

That is 10 times more than you took out.
The oil will replace the volume that would normaly be filled by refrigerant vapour.

Secondly you allowed refrigerant to enter the cylinder while the system was running??
Do you know how much refrigerant there is inside the system because with 900 gms
adding or subtracting a small amount will effect the systems performance.

Lastly while I think on, did you evacuate the system correctly with a vac pump before
you added the refrigerant to remove any air from it?? If you did not that will effect the system also..

taz

.

[Brian_UK]

Also, just because the compressor has a maximum running amperage does not mean that you should charge it to an amperage reading.

It is a capillary system ,charge to sub-cooling.

Did you replace the filter drier?

Why did you remove the oil in the first instance?

[nike123]

It is a capillary system ,charge to sub-cooling.

Did you mean superheat?

[kssoin]

Hi taz24, Brian and Nike123,
Thanks for your posts.
taz 24
The gas was lost because of a leakage. I thought of charging the ac wit R134 but when I looked up on the net , this was not going to be easy, so stuck to r22. I had taken out the oil knowing that r134 would need another oil. The spec sheet of a similar compressor had 1100 ml as oil charge.
Oil taking up refrigerant space is one aspect.
I had cut the old capilary. So the length of the new cap may be a few cms longer. Is the length of the capillary critical and how?
Yes I did vac the system to -20 psig.
Brian
Yes I did replace the filter drier.
Can I increase the subcooling by placing the liquid pipe after the condenser along the base where the condensate collects.
I will measure the super heat and subcooling and post it to morrow.
What should the value of subcooling and superheat be for a 19000 BTU system.

Your help is appreciated.

[nike123]

@Kssoin

You have big problem with oil. You poured new oil in compressor which is not constructed for oil change or similar actions. And in doing so, you did not poured old oil from system. Now you have 1000 ml of surplus oil in your system.
You cannot change oil in rotary vane compressor without use of special tools or without boring hole in bottom of compressor housing.
Al other problems are currently pointless if you cannot correct oil problem.
And, if you want to switch from mineral to POE oil you need to ensure that mineral oil residue is less than 5%.
I don't see how could you do that without flushing or some other procedure like opening compressor housing and frequent oil change.

[K.R.Iyer]

Kssoin,

Are you new to this trade? Which make window AC is this? Why did you think of charging R134a in it? which grade oil did you charge in that rotary? The Copeland recip oil grade is different from a rotary oil. Did you contact the OEM (brand) which made this AC? Are you from some research institute or educational institute? If yes, you may take professional help.

If you have entered the industry very recently, hire 1 or 2 technicians. There are plenty of technicians available in Delhi. with summer temperature already crossing 40C at many Indian cities, your client may not want you to do this R&D job now!!

Just a friendly suggestion to a new entrant. Bear with me if it is unsolicited and not to your liking.....

[kssoin]

Hello K R Iyer,
You are right about temperatures going high!
My wife is my client.
today i have evacuated as much of the refrigerant into the ref bottle.
My ac is a hyundai AC and there are no specs of this on the net nor is the company around as i tried calling it appears that the numbers are not valid.
I will try manouver oil out of the comp by inverting it and pushing N2 . (I will have to braze open a couple of lines though)
I did not use the r134 oil as i charged it with r22. Would you have a clue to how much oil is sufficient?
I am an electrical engineer. I have equipped my self with the tools of the trade.
I dont mind your suggestions, all advice is welcome.

[simon@parker]

er wow no experiancd an ya seem to have a good grasp of wot yr doin oil as mentioned major prob to much as bad if not worse than to little suggest u blow through evap and condenser with n2 as well and vac 30 inches or 2 torr basically as good as ya can get charge slowly may take a little more gas with larger evap hope this helps oh extra gas will be grams not kilos

[Gary]

If you take 100ml of oil out, then you need to put 100ml of oil back in.

You put back in 1100ml, therefore you now need to take 1000ml back out.

[kssoin]

Hi All,
I have charged the aircon today.
I purged it with N2 twice. Pressure checked it to 200psig.
Vacuumed it to -25 psig.
Charged it according to superheat at the evaporator.
After the system was stable with 60psig at suction after the evap, pressure at discharge was 250psig.
the saturation temp at 60 psig is abt 1.2deg C. the temp aof the suction pipe at exit of evaporator was 15.6 deg C(superheat 14.4deg C)
at discharge pressure of 250 psig the sat temp for R22 is 47.22 deg C. the temp of liquid line before the filter drier was 32 deg C (subcooling of 15.22 deg C).
The amps of ac is 8.9A.
Temp diff across the evap is 13 deg C with fan running at low speed.
After evac of the oil i put in abt 100 ml of new oil.
Rh is 25%.
will see how it works on higher RH during July August.
I must thank all you gents who responded to this thread.
Regards.

[simon@parker]

did you get all the oil out you put in ? if you didnt you are going to have problems see how it runs good luck

[Gary]

Hi All,
I have charged the aircon today.
I purged it with N2 twice. Pressure checked it to 200psig.
Vacuumed it to -25 psig.
Charged it according to superheat at the evaporator.
After the system was stable with 60psig at suction after the evap, pressure at discharge was 250psig.
the saturation temp at 60 psig is abt 1.2deg C. the temp aof the suction pipe at exit of evaporator was 15.6 deg C(superheat 14.4deg C)
at discharge pressure of 250 psig the sat temp for R22 is 47.22 deg C. the temp of liquid line before the filter drier was 32 deg C (subcooling of 15.22 deg C).
The amps of ac is 8.9A.
Temp diff across the evap is 13 deg C with fan running at low speed.
After evac of the oil i put in abt 100 ml of new oil.
Rh is 25%.
will see how it works on higher RH during July August.
I must thank all you gents who responded to this thread.
Regards.

Wait until the room is down to temperature, then check it all again. I think you will find that the A/C is overcharged.

[simon@parker]

hi gary am not as technical as you would have thought higher discharge was due to initial run up suction pressure pretty good about right i would have thought as a rule of thumb all the info that is there seems to indicate high load on start how did you come to it being over charged

[frank]

I purged it with N2 twice. Pressure checked it to 200psig.

After the system was stable with 60psig at suction after the evap, pressure at discharge was 250psig.

Seems like your pressure test was not good!

[Gary]

hi gary am not as technical as you would have thought higher discharge was due to initial run up suction pressure pretty good about right i would have thought as a rule of thumb all the info that is there seems to indicate high load on start how did you come to it being over charged

On a hot day we might expect discharge pressure to be higher. On a cold day we might expect the discharge pressure to be lower. Since we don't know the ambient, we can't tell if the discharge is high or low.

Like any cap tube system, the superheat drops as the space comes down to temp. We don't know the space temp so we can't tell if the superheat is right or not.

What tells me the system is overcharged is the subcooling. The subcooling should be no more than 15F/8.5K... 20F/11K absolute tops.

Excessive subcooling means surplus liquid is backing up into the condenser (overcharge or restriction)...
or possibly there is air in the system.

But all measurements are more accurate when the system is down to design temp.

[simon@parker]

thank you gary every day is a school day

[Gary]

thank you gary every day is a school day

For me, too. To live is to learn.

[kssoin]

Hi Gary,
You have hinted at to scenarios. I observe that with suction pressure of 55 psig the disch pressure is 275 psig with an ambient temp of 42 Deg C. and the evap coils 1, 2, and 3 have moisture condensing at the bends. Other pipes are barely cool. Capillary entry is at coil 1 starting from the bottom. If it is having a blockage, how to test it? In this condition the system will take days to reach design temp.at 55 psig the superheat was more than 40 Deg F.
Regards

[Gary]

Did you remove 1000ml of oil?

[kssoin]

Hi Gary,
I've been able to get 800 ml out.
Regards.

[Gary]

Hi Gary,
I've been able to get 800 ml out.
Regards.

Before you started working on the A/C, the oil charge was correct.

The amount of oil added should be equal to the amount of oil removed. This ensures that the oil charge remains correct.

What is the total amount of oil that you have removed?

What is the total amount of oil that you have added?

[kssoin]

Hi Gary,
I took out 100 ml, put in 1100.
I have been able to extract 950 ml. So there is abt 150 ml in the system.
When i started on the m/c the gas had leaked out so some oil must have escaped with the leak. How much oil escaped ?

Regards

[nike123]

Hi Gary,
I took out 100 ml, put in 1100.
I have been able to extract 950 ml. So there is abt 150 ml in the system.
When i started on the m/c the gas had leaked out so some oil must have escaped with the leak. How much oil escaped ?

Regards

If you did not founded oil pool below leaking point, little to nothing.
According to my calculation ,you have now 150 ml of surplus oil which could kill your compressor.

[kssoin]

Hi ,
At higher ambient temperatures 42 Deg C, the discharge pressure was reaching 275 psig and suction was barely 55 psig. As Gary has pointed out that it could be a restriction, I have reduced the capilary from 74cms to 40 cms.( To increase refrigerant flow as the cap is a throttling device, am I right?)
Evacuated the system to -55mm Hg charged the system by superheat method.
At 99 Deg F ambient, the discharge pressure was 265Psig, LP pressure was 65 psig.
Subcooling was (119-103.8)i.e 15.2 deg F and superheat was ( 58-36) i.e. 24 Deg F again high.
I observe that nearly all the tubes of the evaporator are cooling, but 58 Deg F at the suction line is higher.
May I try shortening the capilary further and increase the refrigerant flow through the evaporator and thus bring the superheat to abt 10 to 15 Deg F as suggested by Gary.The Amps are abt 9 to 9.4 but tend to rise to 10 Amps as the ambient temp peaks at noon.
Your posts are helping me a lot understand the refrigeration cycle.

[Gary]

Do NOT cut the cap tube.

If this is the cap tube that came with the A/C, then it is sized for the A/C.

[Gary]

Hi ,
At higher ambient temperatures 42 Deg C, the discharge pressure was reaching 275 psig and suction was barely 55 psig. As Gary has pointed out that it could be a restriction, I have reduced the capilary from 74cms to 40 cms.( To increase refrigerant flow as the cap is a throttling device, am I right?)
Evacuated the system to -55mm Hg charged the system by superheat method.
At 99 Deg F ambient, the discharge pressure was 265Psig, LP pressure was 65 psig.
Subcooling was (119-103.8)i.e 15.2 deg F and superheat was ( 58-36) i.e. 24 Deg F again high.

We can't tell if the superheat is high without knowing the evap air in temp.

And we also need to know the evap air out temp.

[nike123]

I have reduced the capilary from 74cms to 40 cms.
Your posts are helping me a lot understand the refrigeration cycle.

You seems to like learning it in hard way!
You first overcharged with oil and then came here to ask for advice.
Now you cut capillary and again came here to ask for advice.
Since it is obvious that you does not know some things, why don't you try to first ask about them and then act as advised!

[kssoin]

We can't tell if the superheat is high without knowing the evap air in temp.

And we also need to know the evap air out temp.

Hi Gary,
The evap inlet Temp was 83.7 Deg F and the evap out temp was 58.8 deg F

[Gary]

Was this the original cap tube that came with the A/C, or did you replace the cap tube when you replaced the evaporator?

[kssoin]

Was this the original cap tube that came with the A/C, or did you replace the cap tube when you replaced the evaporator?

The system had leaked from thr capillary. So replaced it with same ID and length of 74 cms.
Two pipes abt 2ft of 1/4 tubimg and 2ft of 3/8 pipe was added. as I re routed the liquid line.This added resistance was why i shortened the cap.
How much head pressure is ok for r22 system with ambient of 42 Deg C?
Regards

[Gary]

Hi Gary,
The evap inlet Temp was 83.7 Deg F and the evap out temp was 58.8 deg F

84 - 59 = 25F delta-T. The delta-t should be about 20F. This means you are not getting enough airflow through the evaporator. Make sure the blower wheel is clean and the fan is set on high speed.

Check for restrictions in the liquid line. There will be a sudden temperature drop at the point of restriction. Make sure any drier or strainer in the liquid line is pointed in the direction of flow and that its outlet is tilted downwards.

Wait until the evap air inlet temp is down to about 75F, then take new pressure and temperature readings.

[huskyman]

Hi Gary
I have recently joined re and i was looking for your website but it doesnt seem to be loading up. Can you help me with the website details and where i can get your books please thanks

[Gary]

Hi Gary
I have recently joined re and i was looking for your website but it doesnt seem to be loading up. Can you help me with the website details and where i can get your books please thanks

Try this:

http://prostores1.carrierzone.com/se...com/StoreFront

[kssoin]

84 - 59 = 25F delta-T. The delta-t should be about 20F. This means you are not getting enough airflow through the evaporator. Make sure the blower wheel is clean and the fan is set on high speed.

Check for restrictions in the liquid line. There will be a sudden temperature drop at the point of restriction. Make sure any drier or strainer in the liquid line is pointed in the direction of flow and that its outlet is tilted downwards.

Wait until the evap air inlet temp is down to about 75F, then take new pressure and temperature readings.

Hi Gary,
I have not been able to figure out a way to fix hoses at suction line and compressor discharge to neasure the presures while the window ac is in place. With the ac pulled out the airflow through the condenser is affected.
will try to do it this weekend.
The min evap in temperature achieved is 22 Deg. C
Thenew evaporator is a simple one the one that was replaced had a distributor for the refrigerant. the refrigerant entered it in four pipes while in the new one it enters at the lowest rolls in two pipes one in front and the other in the rear.
excuse me for being silent
Regards

[moh,asif]

hi u removed gas and recharg gas r22 with r12 after 50pis and check com cooling and not thaks hi map

[kssoin]

84 - 59 = 25F delta-T. The delta-t should be about 20F. This means you are not getting enough airflow through the evaporator. Make sure the blower wheel is clean and the fan is set on high speed.

Check for restrictions in the liquid line. There will be a sudden temperature drop at the point of restriction. Make sure any drier or strainer in the liquid line is pointed in the direction of flow and that its outlet is tilted downwards.

Wait until the evap air inlet temp is down to about 75F, then take new pressure and temperature readings.

Hi Gary,
You are right, there were two restrictions in the liquid line. Inthe 3/8 inch liquid line the pipe had collapsed at the bends invards creating the restriction. I re did the bends and recharged the system from the liquid line before the drier with weighed R22.
I was not sucessful in pinching off the charging point the hp line and suction line pressure points. there was leakage from them and I lost the charge.
I used the locking pinchoff tool. Please throww light on how to seal off these points.
Regards

[bunnythorpesean]

I was not sucessful in pinching off the charging point the hp line and suction line pressure points. there was leakage from them and I lost the charge.
I used the locking pinchoff tool. Please throww light on how to seal off these points.
Regards

pinch them off then weld over with silfoss?