Where is the oil hiding?

[Heinrich]

I am rigging a split AC system using the evaporator, condenser and compressor from a window air conditioner. The requirement is to cool the space of a room with no window and no plan to cut a big hole in the wall, and to do it cheap! My bright idea was to hack window aircon that sat unused taking up space since my renting days.

The original unit was 12000BTU, R22, 1ph scroll compressor with a 2-section evaporator with capillary tubes, one per section.
The window ac was operated for about 10 minutes the day before I reclaimed the R22. I recovered 423 grams of refrigerant using a self-piercing tap placed on the low side line after the evap and before the accumulator.
After removing the R22 I proceeded to cut and seal the pipes and to my surprise everything was bone dry, no trace of oil.
My question is: is it possible that the original unit had no oil in it yet it functioned for 2-3 summers?

I plan to charge the Franken-cooler I'm building with propa..errr R-290 and MO but I seem incapable to find MO. What is the magic about ac-mo, is it a bad idea to try W90 gear oil?

Thanks and Cheers!
H

[Toolman]

I am rigging a split AC system using the evaporator, condenser and compressor from a window air conditioner. The requirement is to cool the space of a room with no window and no plan to cut a big hole in the wall, and to do it cheap! My bright idea was to hack window aircon that sat unused taking up space since my renting days.

The original unit was 12000BTU, R22, 1ph scroll compressor with a 2-section evaporator with capillary tubes, one per section.
The window ac was operated for about 10 minutes the day before I reclaimed the R22. I recovered 423 grams of refrigerant using a self-piercing tap placed on the low side line after the evap and before the accumulator.
After removing the R22 I proceeded to cut and seal the pipes and to my surprise everything was bone dry, no trace of oil.
My question is: is it possible that the original unit had no oil in it yet it functioned for 2-3 summers?

I plan to charge the Franken-cooler I'm building with propa..errr R-290 and MO but I seem incapable to find MO. What is the magic about ac-mo, is it a bad idea to try W90 gear oil?

Thanks and Cheers!
H

Dry pipes internally is correct they normally arent dripping in oil unless its the oil return line .

When you say MO I assume you mean "mineral oil" and what is propa..errr R-290 ??

You ask is it a bad idea to try W90 gear oil? Haha you perhaps better go and buy a elcheapo high wall split because i assure you it will run longer than a system thats had gear oil poured into it !!

[Heinrich]

Makes sense, no gear oil.
R290
Oil return line, are you kidding ? not on this puppy. In this Oil should return with the refrigerant flow, through the suction line to the compressor. I would think that the suction line should have some trace of oil, am I wrong?

Cheers
H

[Heinrich]

Now, seriously, my problem is that I can't add oil to the newly re-configured system before I find where the old oil is. I can speculate that all old oil is parked inside the compressor, leaving no trace anywhere else and, as I plan to charge with a compatible refrigerant, I'd just add the gas, but such assumption may cost me the compressor.

Cheers
H

[Brian_UK]

If the oil is not in the pipework that you have cut out then it is still in the compressor.

Even if there was evidence of oil in the pipework there would still be sufficient in the compressor as long as the unit was a fully working model.

[Toolman]

The oil is not hiding its where it should be in the compressor .
If your doing some crazy splitting up of a room aircond ( commonly know as a RAC) that I think you said you were , and extending the noisy bits outside you will need more pipework ,,yes ? You should get away with no more oil being needed but add some anyway , how much you ask ...not a lot try 1/8 cup ( a guess ) . And due to more pipework you will need more gas you say you reclaimed the old gas , i'm impressed , but you probably lost nearly all of it doing this excercise and so you will definitely need more R22 .
You are changing the design of a tried and true design in the roomy so dont be surprised if after all your efforts it ****s itself then you will go and buy a High Wall Split .

[Heinrich]

Brian, Toolman, thanks for you replies. I get it now.
Yes, i am moving the noisy bits outside. The pipes will be 4 ft longer than in the original, i need a bit more R22. On the plus side, the airflow through the condenser will be much better than in the window unit box, that may compensate for the loss of performance due to longer lines.

Experimenting is more fun than just buying/using the right things (as long as no-one else pays for the job) and, done right it works every time about 60% LOL
Cheers
H

[SeanB]

There probably is a gram or two of oil in the evaporator and condenser, but you will not see much as liquid, the gas does a good job of moving it around, and most of it will be in the compressor. You will need a little more, probably around 30ml or so, it will be hard to get that amount off the shelf, so you probably will have to leave it as it is, and figure most of the oil is in the compressor. 400g of R22 is a little low for a 12000 btu unit, it is more like 800g or so for most of the rust boxes I have worked on, so you either have a leak or the valve lost a lot along the way. Go buy a sachet of leak detecting dye and add it to the system when reassembling, it will show up the leaks and add a little oil as well.

[ron_of_orange]

There probably is a gram or two of oil in the evaporator and condenser, but you will not see much as liquid, the gas does a good job of moving it around, and most of it will be in the compressor. You will need a little more, probably around 30ml or so, it will be hard to get that amount off the shelf, so you probably will have to leave it as it is, and figure most of the oil is in the compressor. 400g of R22 is a little low for a 12000 btu unit, it is more like 800g or so for most of the rust boxes I have worked on, so you either have a leak or the valve lost a lot along the way. Go buy a sachet of leak detecting dye and add it to the system when reassembling, it will show up the leaks and add a little oil as well.

Hi SeanB,
Could you perhaps offer a guess for a 16,000btu DX system with a line set that's around 10 feet (one way).


Ron