GE mini fridge conversion (gone wrong)

[abugg]

I've read these forums quite extensively to get a good idea of the steps I need to take to do a conversion.

I purchased a conversion kit in 2006 and was using it in a very ghetto way. I had a keg jammed into my food fridge and packed food all around the keg. It was an apartment fridge that I didn't own so I didn't want to drill it
I decided it's time to reawaken the beast and install a proper setup.

I found a used GE model identical to the one used in this post
https://www.homebrewtalk.com/f51/kegerator-conversion-ge-smr04dasbcs-143712/

I began bending down the freezer carefully and when it was at about 45 degrees the worst thing that could happen happened... I heard gas leaking!
It was leaking from the brazed connection between the pipe that feeds through the back wall and the freezer shelf.

I don't remember reading about the freezer bending step going wrong for anyone so I was fairly confident that it wouldn't be problem.

The general consensus I have heard about a leaking fridge is that it's more trouble than it's worth to fix. I plan to try anyway.
Luckily I know an HVAC guy with the tools to potentially save this fridge with little to no cost.

We r going to rebraze the connection, vacuum the system and add new gas.
If anyone has experience with recharging refrigerant please comment.

A few things that need to be considered.
1. The GE mini fridge uses R134a gas. R134a cannot be purchased without a license in Canada. However, R12a is legal, available in Canadian Tire and is a direct replacement for R134a.

2. There are normally no access valves on fridge cooling systems. I will need to install a saddle valve to tap into the lines to add new gas.

I will post some pics tonight of my progress so far.

BTW, For those interested, I am also modifying the fridge to host a 1/2 barrel by re-framing and insulating the compressor shelf similar to these posts.
https://www.homebrewtalk.com/f51/frigidaire-model-frc445gb-mini-fridge-kegerator-conversion-89013/index44.html
https://www.homebrewtalk.com/f51/frigidaire-model-frc445gb-mini-fridge-kegerator-conversion-89013/index50.html

I'll try to document the process and post as many pics as possible.

Cheers!

 

[outside92129]

Pardon my ignorance, but what is the bending step?

 

[abugg]

Pardon my ignorance, but what is the bending step?

The "bending step" consists of unscrewing the horizontal freezer shelf with all the coolant lines, and bending it down against the back wall of the fridge as seen in the the images of the first link.

 

[Maxkling]

A few things that need to be considered.
1. The GE mini fridge uses R134a gas. R134a cannot be purchased without a license in Canada. However, R12a is legal, available in Canadian Tire and is a direct replacement for R134a.

They are defiantly not a direct replacement and you should look into the differences. Ive never gone from R134a to R12, its weird how your laws are in Canada, as R134 was created to replace R12. In fact the Montreal Protocol makes it almost impossible to obtain R12, and you need a special license. You should be able to purchase R134a with no license anywhere, it is a non-ozone depletion compound, and isn't restricted in small quantities.

 

[abugg]

Note the 'A' in R12a. R12 (freon) is much different than R12a.

I have a couple links for reference.
http://www.duracool.com/Duracool/refrigerants.html
http://www.modifiedcadillac.org/forum/index.php?topic=4295.0
http://grassrootsmotorsports.com/forum/grm/duracool-or-r134a/23302/page1/

 

[Maxkling]

Rodger.

Never heard of R12A...

So are you a 100% sure you cannot purchase R134A in Canada?

 

[justtaint]

Dumb question, but did you let the freezer shelf warm up before attempting to bend it?

 

[abugg]

I am positive about the R134a not being available without a license in Canada.

Dumb question, but did you let the freezer shelf warm up before attempting to bend it?

Yes, the fridge had been unplugged and sitting in my warm garage for almost 24 hours.

 

[abugg]

Here is my bent freezer failure. Note the tuck tape placed as a weak attempt to stop the gas from leaking

I read that brazing aluminum, especially thin aluminum can be quite difficult without low temperature brazing material, which I didn't have quick access too. I found out that an epoxy, J-B weld, is commonly used to repair punctured evap lines from someone using a knife to accelerate the defrosting process .

I bought some and applied it, seems to be holding but I haven't had a chance to vacuum the lines yet.

I made a 1/4 template of a keg with some added tolerances of course.

Traced the template onto the plastic.

Cut it out starting with the inner plastic, then moved on to the foam, and outer black “cover” material.

Save this piece to reuse for insulating the bottom of the unit.

 

[abugg]

Next I started working on moving the compressor. I used some L-brackets to create an extended platform shelf to hold the compressor in its new position.
This is what it looks like protruding out the back

I bought screws with the same thread and diameter to screw into the existing threads to anchor the platform. I then bought some nuts to attach the compressor to the L-brackets. Everything was secured with lock nuts in case of vibration from the compressor.
This is what it looks like from inside the fridge. The wood that you see is just the plywood I was working on top of and is not related to the fridge.

Next, I created a template of the floor piece out of paper and then traced it onto aluminum sheet metal. I used aluminum instead of steel because I didn't want stuff rusting. It was a little more pricey but it's easier to work with and I will avoid rust in the future.

Cut out the piece... looks like I didn't do a perfect semi circle. No problem because people won't see it anyway.

When I placed the reused piece of foam to insulate the floor, I had to notch it to accommodate the L-brackets.

I put silicon on the under side of the metal and placed it into position glued to the foam and overlapped the aluminum metal by about 1 inch. I used an empty propane tank to hold down the metal while the silicon dried.

 

[mcubed45]

that seems like a lot of work you're doing when you don't even know if it will still function.. i haven't read of anyone succesfully fixing a cracked coolant line. best of luck tho.

 

[rekoob]

I would have to agree with the "not sure if it will work" part of the last statment. However, if all goes well with the patch, I think you will have a nice set up here. I will keep my fingers crossed for your patch. Good luck!

 

[brewingmeister]

that seems like a lot of work you're doing when you don't even know if it will still function.. i haven't read of anyone succesfully fixing a cracked coolant line. best of luck tho.

Yeah it seems like you are spending a lot of time and materials on a paperweight. You have a lot to do to get that thing running again.

I wish you luck though, more difficult things have been accomplished . I'm rooting for you though, I haven't seen too many mini fridges modified to accommodate a 1/2 barrel.

-cheers

 

[abugg]

I was skeptical about being able to repair the leak but then I found so many reports of successes with J-B Weld. I didn't want to carry on an waste my effort but I just had a feeling.

The patch is ALL GOOD! I pressure tested it to 50 psi and it held it without any problems. We weren't sure what pressure the evac lines normally reach; I thought it was about 15psi but 50 seemed like a good number.

I vacuumed the lines down and it's still holding. I had trouble finding the proper connected to couple a can of R12a to my piercing valve with a 1/4 inch connector.

I might call up a shop and see if they can recharge my lines. It's all vacuumed and has the access valve installing so it will be a quick job and hopefully they won't charge a lot for it.
I'll post some more pics of my progress and an update of the gas recharging.

 

[Maxkling]

that seems like a lot of work you're doing when you don't even know if it will still function.. i haven't read of anyone succesfully fixing a cracked coolant line. best of luck tho.

Cracked lines are a very common issue... and are fixed all the time. In fact aluminum if you have the right flux and solder is a very easy fix.

 

[pollox87]

You should be able to find the amount of charge you need from the manufacturer, if not you would have to do it yourself.

If you are going to charge it yourself you should get a few thermocouples to attach to your suction and discharge lines, as well as a gauge set to hook up to the ports you attached. You will also need a saturation table or calculator. This matches up temperatures with pressures at the boiling point so with both you can tell if the refrigerant is liquid or gas.

Connect the high side gauge to the high side of the compressor and the low to the low.
Attach a thermocouple before the expansion valve.
fill the system with a moderate amount of refrigerant from the gas side of the tank. (10-15 PSI??, this is where you may want some other advice, I work on much, much larger systems than this)
Turn on the system, if the compressor starts making nasty noises turn it off, you may have added too much or too little.
Take your pressure reading from the high side and find its saturation temperture. Compare it with the reading on your thermocouple. Continue adding until you are get a reading on your thermocouple lower than the saturation temp for the current pressure. (this will change) Give it a few minutes in between adding Refrigerant to make another change.
Verify that you are not close to flooding back liquid to your compressor using the charts and thermocouples again.

Hope it helps. and remember, even if you blow it up, you still had fun messing around, right? Hope I could help.

 

[abugg]

The issue I am having now is finding an appliance repair store in Ottawa that is willing to charge the gas. I can't even get a price from anyone because they say nobody does that any more.

My other (preferred) option is to fill it myself. The problem is the can of gas that I have is made for automobile applications and I don't have or know where to find something to pierce the can and connect with a 1/4 inch connection to my gauges.
In this youtube video, there is a picture of it around the 2:00 and 3:40 mark. It's a green adapter that wraps around the can. The gas I have looks exactly the same as that R134a can at the 2:00 mark.

 

[abugg]

pollox87, thanks for your tips on filling the gas.
I managed to find the right adapters and couplers that I need to attach the gas to my gauges.
I only installed a saddle valve onto the low side. I won't be able to measure pressure on the high side while filling.
There is a label on the back of the fridge that shows the pressure at 70 degrees F.
Should I put that much pressure of gas into the low side of the system before turning it on?

I also read something about adding gas with the compressor running until the evap coils in the fridge frost over but before the coil outside the fridge becomes frosted. Has anyone heard that before?

 

[abugg]

Low side of the compressor with the saddle valve attached.

Foam insulation installed and sealed.

Aluminum sheet metal installed on top of the foam for strength, moisture and mechanical separation and to look good.

Installed aluminum sheet metal to replace the inside panel of the door.

There won't be enough room in the fridge for a 1/2 barrel and 5lb CO2 tank so I ran the CO2 lines out the back.

The inside of the door after the tap and drip tray have been installed.

And here is the finished product!

 

[Junkster]

Your data tag shows 1.8oz R134A - that's a tiny amount & the charging hoses probably hold that much. These small systems don't have a liquid receiver and the charge is critical. It would be very easy to overcharge this unit. Try calling some HVAC service places that are equipped to accurately measure or weigh it & they may charge it for you for a very reasonable price. Even though your JB Weld patch is on the low pressure side, it will still see fairly high pressures when the compressor stops & the high & low sides equalize through the cap tube. You may want to pressure test at 120-150# before you call it good.....

 

[brewingmeister]

I like the modifications to the box, looks good. I hope the cold parts go as smooth. The JB weld may have to be altered, I don't have any experience with it but I'm skeptical of it's use. If you have the tools to solder that may be the way to go. Someone earlier said earlier it's easy to fix the lines and make it right but the coolant is going to be the main pain.
Box mods look nice though.

-cheers

 

[lordbeermestrength]

JB weld is pretty amazing stuff. I saw it used once to repair a high vacuum leak. It worked and held vacuum at under 1.0e-6 torr range.

 

[Dwain]

abugg,
This thread show Trouble using 134a. I know you can't get that, but the repair info is good. - Dwain

https://www.homebrewtalk.com/f51/did-i-just-ruin-fridge-202271/

 

[abugg]

As suggested, I pressure tested the system again, this time at 120 psi with nitrogen. The gauge didn't move so I should be good for real this time.

I vacuumed the system and then started adding the gas. Unfortunately I didn't have a scale that was accurate enough for under 1.8 oz.

I'm not sure about my pressures and the way the compressor is behaving.
The compressor runs very hot... too hot to touch.

I'm not sure how to interpret my specs for r134a to adapt to r12a. When using r12a as a replacement to r134a, you aparantly need only 40% of the weight of r134a. Not sure how that converts to pressure if it does at all.

The way it is now, my fridge got really cold, it froze the glass of water I had in it at about -10 deg C. about 3/4 of the evap coils in the fridge are frosted over.
So if I try to set this up according to feel. Should my evap lines in the freezer be frosting over or does that indicate too much or too little gas?

 

[Junkster]

Some compressors do run kind of hot, but if it's overcharged you may be working it too hard. If it gets too hot, it may trip out on its internal thermal overload protector. If you can, measure the amp draw for the unit and compare it to the nameplate rating. That rating is the worst case scenario under max load - typically, they draw somewhat less current than that.

I'm not sure about the frosting pattern relative to the proper charge level. Do you know how that compares with operation prior to mods? Also, do you have gauges to monitor your low side pressure while it's running?

 

[abugg]

I have gauges to measure the low side pressure while running. I added enough gas to make it stabilize at ~0 psi when running. I have tried to find the RED TEK® 12a conversion chart that is mentioned on their website but I can't seem to find it... All the pressures that they specify are for automobiles and seem high to me...

I'll try measuring the amp draw to see if it's being overworked. If the amps are maxed and it is being overworked, is that a clear indication that there is too little or too much gas?

I don't know about the frost patter before hand. I wonder if mini fridges are even supposed to be cold enough to form frost.... Maybe someone knows the answer to that?

 

[Junkster]

Usually, when the pressures go up the compressor is working harder and the amp draw increases as well. I'm thinking 20-25# on the low side is closer to what it should be if the evaporator is 15 degrees or so below the desired box temperature. Does this unit have an evaporator fan and condenser fan?

 

[abugg]

It's a natural draft box. No fans on the evaporator or the condensor.

I managed to find this chart. http://www.redtek.com/win_12a_vaporpress.html

Since the box is bent down against the back, I'm not sure exactly what box temp I am aiming for... Is the entire fridge now considered the "box"? So the evap gas temp needed might be 20 below the box temp instead of 15 because of the larger volume to cool?
Going back to the chart, if I have 0 psi (bubble, which should be the evaporation pressure) will that make the evap gas -32 degrees C? Is that the correct way to interpret it?

And so if I want about 0 degrees C in the fridge, would I make it ~19 psi for a -15 to -20 deg C for the evap gas?

 

[Junkster]

Yeah, I think you're interpreting the chart ok.

Since the compressor doesn't have a condenser fan moving air over it, its temperature may seem hot - double check the amp draw if you add additional refrigerant.

Also, if you're using the original control & it was attached to the evaporator, it probably won't work correctly in the free air space of the cooler. The cut-in & cut-out temperatures are for when the sensing bulb is in contact with the evaporator.

 

[abugg]

Yeah, I think you're interpreting the chart ok.

Since the compressor doesn't have a condenser fan moving air over it, its temperature may seem hot - double check the amp draw if you add additional refrigerant.

Also, if you're using the original control & it was attached to the evaporator, it probably won't work correctly in the free air space of the cooler. The cut-in & cut-out temperatures are for when the sensing bulb is in contact with the evaporator.

The condenser lines are built into the two sides of the fridge so they are basically insulated so it makes sense why the compressor may run hot.

I am going to add some more gas tonight so that the entire evaporator box frosts, that should be around 19 psi.

Thanks for the help!

 

[sj_engr]

Low side of the compressor with the saddle valve attached.

Thanks for the heads up on the bullet valve. Grabbed one from Granger ($4) and a R12->R134a adapter ($6) from Auto parts store. Used some quick charge 134a on the wine fridge I was working on and appears to brought it back to life.

 

[abugg]

That looks great! Good to know that someone else has been able to revive a dead fridge.

 

[MDHarris]

Last night I did this and brought my fermintation chamber back to life. I'm sure there is a leak, but i can put 5 bucks of 134a in once a month to keep it running till I find a deal on another freezer. I spent 55$ on a guage set from Harber Freight, 12$ on a can of 134a from the auto part store, got the line tap from a friend, and the can tap was 5$. This is way less expensive than a repair mans service charge.
If my coolant was completely gone then it would take about half of a can to fill it.