Modding my broken minifrige into a kegerator

[stockwes]

Ok, I have a mini fridge that got a leak in it during moving, there is a small crack in the current evaporator, as far as I know all the gas has escaped as it has sat around almost a year.

I am an avid home brewer with no kegerator; this mini frige was originally intended to serve this purpose however there was not enough clearance to fit a keg with the evaporator/freezer in its stock location.

In an attempt to save the broken fridge and make it work for me I had the idea of removing the existing freezer box evaporator and replacing it with a length of small copper tubing located where it would not effect the keg space. I have enough copper skills to form the evaporator as well as solder it in place in a way that it will not leak.

The portion of the project I am unsure of is the recharging of the coolant. I have access to an a/c manifold as well as vacuum pump that is equipped for r134a, which is the gas the fridge says it takes; I just have no one to show me how to use it.

Is this even possible?

The fridge says it takes

2oz of coolant
High side 250psi
Low Side 103psi

I would think that the 2oz means nothing anymore as I am changing the volume of the system.

My understanding is that:
1.Attach piercing valves to high and low side in locations shown in picture
2.I hook up gauges to high and low
3.pull a vacuum
4.close valve
5.remove vacuum pump and attach coolant to sealed system
6.purge coolant line
7.put in a little coolant
8.turn on compressor
9.Slowly fill until pressures reach the manufactures specs.
10.close piercing valves and run fridge as normal

Am I missing anything? Does this seem correct? I have no idea where to locate some of this info. Any help would be appreciated.

Thanks for reading

[toprunner]

It will work they way you say except for one thing:

The correct charge of refrigerant cannot be estimated by reading the pressure as guide.

For massproduced household products its an empiric process and if you change the system you should use a sightglass before the capillary or do a lot of your own testing.

You should also make sure you have the correct superheat in all load conditions or add some device that aids the superheat.

[stockwes]

"The correct charge of refrigerant cannot be estimated by reading the pressure as guide."

You say i can do via my own testing... Will my idea work to at least make the system cool? If not what method would you recomend that does not involve a ton of calculations or equipment? This will be my first refrigeration project of any sort so i would like to keep it basic.

I am not concerned with obtaining the ut most efficiancy, all i want is a fridge that will get my beer cold, be safe, and work for a year or two until i can obtain something better.

Thanks you your reply. Any information is appreciated.

[nike123]

The fridge says it takes

2oz of coolant
High side 250psi
Low Side 103psi


9.Slowly fill until pressures reach the manufactures specs.

Pressures here are max pressures at witch that particular part of system could be exposed and not running pressures of system

[nike123]

Is this even possible?

It is possible but if you are not refrigeration technician with lot of experience, than it is almost impossible in economical way, and at same time you don't know how long it will your investment last.
Throw away that fridge, find some appropriate new cheap unit with 2 or more years guarantee or working used and convert that to your dream kegerator.
http://kegman.net/rc.html

[mikeref]

You will find the capillary tube runs inside the suction line and you will have to recover all of it, then the copper tube will have to be of the right length so you don't have floodback if it is too short or excess superheat from it being too long. Should make an accumulator on the end of your copper evap. to prevent floodback on startups. replace the drier. copper to be 5/16, no bigger and i would not use a sightglass for this critical charge system. Hmmm, evaporator tube length? I'd need to know the compressor capacity at -5c. cheers..

[mikeref]

Oh, by the way, on your fridge photo, where you marked hi valve, that is a tail connecting directly to the low pressure side. Forget about fitting a piercing valve for highside evacuation,they always leak.You can evacuate through your low pressure connection

[stockwes]

So that tail that sticks off the end is the low side? I dont need to pull vaccume on both sides? Low only would be sufficient?

As for the compressor, it is an
LG NSA36LACG
Other than that i know nothing.

The Copper in the system is all 3/8 od (except for the capilary tube) so i was going to make the new evaporator out of the same size simplifing connection. I have a ton of copper odds and ends so i can make whatever i need at no cost. I was going to run it in at the bottom of the fridge and put the whole thing over the hump allowing max area in the top.

Mikeref, What is the accumlator you speak of?

I am takeing on this project because i have all the materials except for the r134a. If i can get any life out of this fridge it will be worth the $10 i spend on this... I know i am inexperienced with this sort of work however there is only one way to learn. Worst case i am out the $10 and i learned a bunch about how a fridge works. So thanks to those who have given information. It is a big help

[mikeref]

Hi Stockwes,If you could post a photo of your evaporator and/or tell me the length of 3/8 tube you are using, it would be helpful. For a system that size pulling a good vaccum through the low side is sufficient.The reason for changing the filter/drier is to keep moisture in check,(an open refrigeration circuit for that period of time is bound to have respirated and pulling a vacuum alone may not be enough. cheers

[stockwes]

Here is a photo of the evaporator.
I also put a photo of the compressor up.

I will try and explain my plans, the red and blue line represent the 3/8 od copper coil that will be inside of the fridge. The lines start where i was going to do my soldering.

The blue line is the one that needs to connect to the tiny tube, which runs inside the bigger tube. My thought on doing this was to cut the tube where you see the black spot, cap the tube pointing up and soldering the 3/8" to the other side, connecting the new evaporator to this line. The return side will connect lower, below the cut completing and sealing the circuit.

As for the length of tubing, i will use whatever it takes. I have at least 50 feet or so so i can use any appropriate amount.

One more stupid question, you speak of a dryer, accumulator, filter... Are these all the same thing? What portion of the system is this? Is this the larger tube the condenser flows into and the tiny capillary tube flows out of? What does replacing this entail?

Thanks again for your help.

[mikeref]

Hi Stockwes,firstly, if you look into the the back of the evaporator(inside the fridge) you will see a round white pipe that flattens out and a small round tube exits then enters the network of raised oval shaped lines..that small tube is the end of the capillary line that starts way back at the drier, at the back L/H side of the fridge, the full length of this capillary has to be recovered or you won't be able to proceed. I would install an off the shelf SP#1 cut to calculated length, but in your project you need the factory set capillary.Thinking ahead, should this project play out, you will still need a qualified mechanic to gas up and leak test your work, what's your thoughts?

[southline]

I'll do it for you if you make me some beer!!