First off, you'll have to see if it is aluminum, copper OR aluminum coverinr the copper.
If it's aluminum over the copper, than you'll have to scrape the aluminum back to expose the copper.
If you've a novice with Brazing ...you should NOT braze!!! The hotter the copper becomes, the more you create carbon on the INSIDE of the refrigeration lines which can later CLOG the orifice/metering device. You can also melt a huge hole if it is aluminum. There are fluxes for brazing for use with refrigeration. It's white, semi-chaulky paste.
I'd use an Acetylene torch with a "low-temp soldering tip" and not a "hi-temp Turbo tip".
If it's aluminum, you have to TIG weld it..... and it's probably too thin to attempt that and will just create a larger hole so it's garbage at that point usually.
There USED TO BE an epoxy product that you could use to seal refrigeration leaks but I haven't seen it in a long time so I think it's no longer available.
If it's copper, then get either "Stay-Brite", "Stay-Silv" OR "Bridgit" SOLDERS that contain higher amounts of SILVER and can close most gaps that aren't ginormous. Be sure not to overheat the solder and "drip" solder in the hole. If you heat up the copper too much it will actually burn and become brittle or just become a bigger hole after it melts away.
If you use "brazing rods" then you'll have to run Nitrogen thru the lines at about 0.5 PSI or so, so that carbon doesn't form inside the refrigeration lines. The trick is to have enough nitro going thru the system so you don't cause carbon flaking & NOT cause another leak in a new solder joint by the nitro pushing thru it and causing one.
IF THE OIL/REFRIGERANT/FREON IGNITES..... IT CAN SHOOT OUT FLAMING OIL AT YOU AND CREATE HIGHLY POISONESS PHOSGENE GAS THAT IS PRETTY DAMN BAD and POSSIBLY FATAL IF ENHALED!!! SO USE EXTREME CAUTION AND TAKE PRECAUTIONS OR HAVE SOMEONE ELSE DO IT. IT'S PROBABLY CHEAPER TO REPLACE THE A/C.
Brazing rods are made to withstand 1500 PSI and so are the above listed solders. Most solders are not made for these pressures so use one of the name brands above.
You have to sand it clean and use just a "TRACE" amount of FLUX made by one of the Solder manufacturers listed above. You do NOT want flux going inside the tubing.
NOW... comes the fun stuff. You have to ADD (2) "service ports" (like a schraeder valve on your car tires to fill with air).
One has to go on the "Suction/low pressure side" and one has to go on the "Discharge/high pressure side" and you will either have to cut in "T's" with service ports OR "drill" small holes in each line (being EXTREMELY CAREFUL NOT to let any of the copper shavings to enter the refrigeration lines) and solder on "pigtails" with schraeders on them... and then follow the same rules of sanding, fluxing & soldering... (in the case of cutting in "T's", you will only flux the MALE ends of the pipe and NOT the females. Consider using a shop vac while drilling if you're going that route. Google up a "air conditioning piping schematic" online so you know what I'm talking about.
The "discharge" line may have a "filter/dryer" (typically either a black, blue or grey component that will have to be replaced OR sometimes it's just a swelled up section of copper that needs to be removed and replaced with a new filter dryer for that size system). It has to be replaced because moist air has gotten into the system and once that collects in the "media" that is inside the filter/dryer, it can release that moisture into the refrigerant system and screw all of your hard work in the end.
Now you'll need to pressurize the system with Nitrogen (so you'll need a nitro tank and regulator and refrigeration guages) and pressurize the system until you reach 100PSI and leave it in there for at least a day typically. If no leaks after 24hrs than you're good to go to the next step. You can rush it and do it for less BUT tiny leaks make it past Pros all the time so the best thing to do is wait 24hrs. Some leaks won't show up even after 24hrs because they're so minute. 1-2 PSI fluxuation after 24hrs is OKAY.
Now you need Refrigeration Guages and a Vacuum pump and vacuum the system for about 2 hours and bring it to -30 Inches of Mg.
Now you need R-22 or R-410a depending on whatever refrigerant/freon the system was made to run on and go online and get a "temperature/pressure chart" and possibly a "subcooling" & "superheat" chart for the type of refrigerant being used. These charts will make it easier for you to charge your system. You'll need thermometers to use the charts.
Best of luck!
Typically a $500-$1000 repair.
$200-350 in material.
3-5 hrs minimum of labor (typically) @ $100-175/hr.
$65-$150 just for the Service Call
