Fridge Repairs


adsm08

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I'm gonna put this here because technically it is an AC repair.

So I picked up a free mini fridge that had a big hole in the evap coil. I got a new evaporator, now I need to braze it into the system. This is a procedure that I only have a passing familiarity with, but from what I understand it is similar to soldering, just with fewer irons and more heat.

I am practicing with the damaged evaporator and some copper brake tubing I had around that happens to be the right size. I am having issues getting it to take. All the videos I have watched and instructional articles I have read say my heat should lead my filler rod, but I can't get the rod to melt unless I keep it in the heat, which so far has only resulted in lots of sparks and boogers that didn't seal, or even hold. I can break them off with some pliers and pull my practice pieces apart. This is leading me to believe that I have a less than optimal filler metal for my application.

So what I am trying to do is braze a 1/4 ID copper line into a 5/16 ID copper line. What is the best material and rod size to do this with?
 


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Denisefwd93

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I'm gonna put this here because technically it is an AC repair.

So I picked up a free mini fridge that had a big hole in the evap coil. I got a new evaporator, now I need to braze it into the system. This is a procedure that I only have a passing familiarity with, but from what I understand it is similar to soldering, just with fewer irons and more heat.

I am practicing with the damaged evaporator and some copper brake tubing I had around that happens to be the right size. I am having issues getting it to take. All the videos I have watched and instructional articles I have read say my heat should lead my filler rod, but I can't get the rod to melt unless I keep it in the heat, which so far has only resulted in lots of sparks and boogers that didn't seal, or even hold. I can break them off with some pliers and pull my practice pieces apart. This is leading me to believe that I have a less than optimal filler metal for my application.

So what I am trying to do is braze a 1/4 ID copper line into a 5/16 ID copper line. What is the best material and rod size to do this with?
You don't have to braze it! just clean the in and out really really well using smidge of flux and 95/5 solder or silver bearing solder. it'll hold you can also use a reducing flare connection.
 

adsm08

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you can also use a reducing flare connection.
You mean like for brake lines? Because I can flare the crap out of brake lines. I kind of figured that a flared connection wouldn't seal well enough to hold refrigerant, or I would have gone that route already.
 

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With copper to copper you clean the outside and inside of connection, emory cloth
Put flux on inside and outside
Put connection together
Heat connection first, heat it evenly all the way around, I use propane torch, then apply SOLDER
Solder will be sucked in and around connection if temp is correct, flux does that part

I think Denisefwd93 was referring to an adapter for the 1/4 ID copper line into a 5/16 ID copper line, so two solder joints

Soldering two connections close together should be done at the same time

Solder doesn't seal wide gaps well, not sure you could expand the 1/4 copper out far enough for tight fit with 5/16, if you could find a copper sleave, that goes over the 1/4 and into the 5/16 then that might work, as a work around, lol
 
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Denisefwd93

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You mean like for brake lines? Because I can flare the crap out of brake lines. I kind of figured that a flared connection wouldn't seal well enough to hold refrigerant, or I would have gone that route already.
Yes the only difference is you don't need to make a double flare so you leave the little adapter off, if you go to a refrigeration supply you can get reducing Flair nuts and fittings but you're not likely to find anywhere else a

Ron is right, I just suggest you not get flux on the inside if you can help it keep it on the back of the male end this way you don't get any wax inside the system.
 

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Ok, I think I get it. I am still practicing some of this on the junk parts before going at the fridge itself.

The lines may not be actually 1/4 and 5/16, it is a tight fit, as these are OEM parts mating together in the OEM style. It's just the sealing the connection without cooking the lines part I am having trouble with.
 

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Most small and domestic units use aluminum and at some point after it leaves the evaporator it changes to copper which is usually a unique type of joint.

Always in refrigeration tubing goes by the OD. Plumbers use the ID of the same tubing sizes,. There are two sizes that you most likely will not find in any Home Center which would be 5/16 and 3/4 OD and in rare cases there's a third 3/16 od.
Ok, I think I get it. I am still practicing some of this on the junk parts before going at the fridge itself.

The lines may not be actually 1/4 and 5/16, it is a tight fit, as these are OEM parts mating together in the OEM style. It's just the sealing the connection without cooking the lines part I am having trouble with.
 

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This is not taking on my practice pieces. Now all I have on hand is powdered brazing flux, and the piece of scrap brake line has nickle in it. I also don't have a propane torch, I am running a #2 welding head on my oxy/acetylene torch and turning it down as low as it will go.What effect are those factors going to have here?

The bigger line is def 5/16 ID, because I get the same tight fit on the line at the compressor (guessing it's the compressor) and the piece of brake tube I am using, which is a known 5/16". The inner piece looks to to be 3/16 or 1/4 ID.

The evaporator itself is aluminum. There is a huge ugly booger job under the paint on both the old and new units where the line comes in. The line is definitely copper.

I think I am likely to just text my BIL and have him grab me a those fitting since he works at an HVAC supply store. I would still like to figure this out and develop a new skill though. I'd just rather do it before I empty my torch tanks.
 

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Well since you have a friend that works at one of those places have him get you a stick of brazing rod with silver in it I think it's called silfos.

the trouble with high heat on copper is the oxidation and the black flakes it makes, that's why most people in the trade just use soft solder it is strong enough.

Many of the small Italian compressor is on these little refrigerators also have steel tubes for the connections in which case you have to use Silver solder and silver solder flux to put copper to steel. It's amazingly complicated for something so little isn't it? But like everything, it's done in a factory to save fractions of pennies on hundreds of thousands of units.
 

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It is amazing what they make us go through for simple stuff.

I am definitely making a copper on copper joint here, unless like my brake line, someone used and alloy in one or both of these lines.
 

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Go buy a burnzamatic propane torch. Great for soldering copper. If you need to braze something, pick up some MAPP gas for it. Also good for finding vacuum leaks on your Ranger.
 

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You can do it!

Cleanliness, flux and practice.

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adsm08

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Well I talked to my BIL and he thinks a big part of my problem is the wrong filler metals. He said he has a few rods left over from when he was an installer that he'll give me, so I'll try again this weekend.

I might go raid my dad's garage, I know he has a few propane bottles laying around.
 


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