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Phil, Shop owner
Category: Appliance
Satisfied Customers: 8675
Experience:  Degree, Mech. engr. shop owner. 51 years experience
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how to weld evaporator coil of a sub zero refrigerator

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how to weld evaporator coil of a sub zero refrigerator
Welcome to Just Answer!

You can purchase aluminum alloy fluxed rod for welding aluminum evaporators at 'Air conditioning and Refrigeration Wholesale houses' It is still very tricky business it can end badly without some prior practice.

You can also buy hot melt epoxies that have about a 90% long term success rate on aluminum evaporators... Many manufacturers have been using these epoxies, hot melt and some that just cure over half an hours time with no heat applied at the same wholesale houses, or retail at Johnstone Supply. The epoxies used in copper and aluminum pipe joints seem to have better reliability than soldered joints.

Let me know if you need any further help with that, we can go from there as necessary

Phil and 3 other Appliance Specialists are ready to help you
Customer: replied 4 years ago.

I don't know what kind of material made the evaporator on refrigerator side (I know the freezer side made by aluminum), can you check online to see as they painted black:

Hello again, the fitting looks like copper, it is a photograph, if it was aluminum it would not photograph copper colored.... we know that the suction line is copper. That is the most reliable combination when it comes to field replacement items.

The chances that 15% sil-fos (1,200 degree F solder that comes in flat sticks) will work are in the 99% range.

I would buy the coil, then on the very unlikely chance it turns out to be aluminum (1% chance or a lot less) I would buy an epoxy at an appliance repair wholesale house rated for that application.

Either way it should not be a problem for you, unless you are not used to working with sil-fos in which case I can coach you on that.

If you wish to rate my answer so far *positively I will hold the question open for you for any follow up you need.


Customer: replied 4 years ago.

I did not understand the whole thing. what kind of material you think I can weld for this evaporator? Can I use torch and lead as I use to solder the copper pipe? I need your detail so I can do it right. Thank you very very much!

Customer: replied 4 years ago.
Relist: Incomplete answer.

Hello again, On this end I get tied up 6 or 8 questions at once, and often have to research details on a there can a wait, especially over night, I can continue with you if you like, Let me know.

You do not have a complete answer until you are fully satisfied, I generally stay with a customer as long as necessary, and offer extensive training if needed.

If the fitting is copper as it looks to be and the suction line attached is copper..and if you are good with an oxygen -acetylene torch then '15% silver silflos works very well, its hot though and can melt the two tubes connections shown in the picture of the coil....

so that, in those cases a product called 'stay brite,0.3% silver that melts at 450F is a good choice' you can use a map gas or propane torch for that (the fuel comes in a wine bottle sized tank, the torch head screws onto the tank)


Do not use lead based solder commonly used with water lines. The system must be ventilated to outside air during the soldering process... but for as brief a time as possible... a few minutes at the most, then the refrigerant drier will need to be replaced.

Let me know if you want to continue with me or not, we can go from there or I can opt out,


Customer: replied 4 years ago.

I try to leave a positive rating but the website denied.

Can you send for me a link so I can rate again?

Thank you


Hello again, your *excellent rating went though just fine... our server has bugs once in a while.

Let me know if you need any more information or coaching on the soldering process.and your range of options..

Customer: replied 4 years ago.

Hi Phil,

I don't want to waste your time, I am waiting to receive the evaporator... as soon as I receive it I check the material and I will get back to you so you can advise me what to do.

Thank you very much for your time.


Good plan,

Be sure not to remove the old coil until you are ready to put the new one in, these systems cannot be allowed to sit open to the air for more than a few minutes.

Customer: replied 4 years ago.

Hi Phil,

I got the evaporator today and I believe it is made by aluminum. I have experience for soldering copper pipe and PC boards but I have not done any evaporator yet however if you tell me the right stuffs to use for this kind of material (aluminum) I believe I can do it.

You may check with some refrigerator technicians and give me more info.

Thank you very much and best regards,


Hello again,


You can use a refrigerant line rated epoxy to connect the aluminum to either copper or aluminum tubing. You can buy that in a kit from any appliance repair wholesale supply such as Johnstone Supply or any HVAC and refrigeration supply wholesaler in your area.


The kit has some sand cloth, instructions, a small container of acetone for cleaning the area and two tubes of the epoxy mix (the epoxy and the catalyst).


Welding aluminum is well beyond most peoples skill level.


Be sure to replace the refrigerant drier, and evacuate the system using a vacuum pump before recharging the unit with specified number of ounces of refrigerant on the refrigerator name plate. Use the same exact refrigerant.


You will need a map gas torch and a stick of silfloss 15% silver to change the refrigerant drier if it is not fit with flare nuts on each end... point the outlet of the drier *down toward the outlet when replacing it.


Use plumbers sand cloth only on the copper when fitting a new drier. Adjust the flame on the torch so that it makes the copper shinny under the flame. practice on some scrap first.


If you need a source for the epoxy, tell me which direction you are from the center of the nearest city and I will find a source for you.











Customer: replied 4 years ago.

Hi Phil,
I live in Brentwood, NY 11717, can you send for me some links so I know exactly what it looks like and where to get it please. In case I want to weld the aluminum, where can I get the materials and can I use the torch that I bought from Homedepot?

Thank you,


Hello again, there are several different brands of the epoxy made for this use, a little bit bigger than a package of cigarettes.


Ask one of the more experienced looking countermen to show you the options... you want a 2 part epoxy mix for those socket fittings, not a hot melt.


Johnstone Supply - Farmingdale #214 135 Schmitt Blvd, Farmingdale, NY ‎(NNN) NNN-NNNN‎ · Category: Air Conditioning Contractor 1 review · "Wholesale distributor to the HVAC, refrigeration and property maintenance industries." -




United RefrigerationXXXXX Farmingdale, NY ‎(NNN) NNN-NNNN‎ ·


CLICK HERE FOR ONE OF THE REFRIGERATION/ ALUMINUM/ COPPER RATED EPOXY KITS.. there are several others ask the counter man which one they carry and sell the most of.




Both of these stores carry the special flux coated welding rod made for aluminum, read the package as to what temperature torch is required.. anything that melts under 1,000 deg F can be done with a map gas torch from Home depot... tell the counter man what materials are involved all aluminum or copper and aluminum, he will show you the relevant products. I recommend the epoxies though.




Before you disconnect the old evaporator coil it might be a good idea to tell me why you are replacing it. The only valid reason for replacing the coil is if it has a refrigerant leak or corrosion that leaks... otherwise if it does not cool the problem is a bad solenoid valve, thermostat, or clogged capilary tube that feeds the coil


Let me know about that.