Sorry guys but you cannot use silver solder on
aluminum the melt point is too high, wrong metal to solder
aluminum. If you want to solder it, it takes a special rod.
Ok here is the redneck solution with out calling the ac guy. First use something like jb weld, sealall, or the expoxy like the man mentioned above. Clean and clean again before use. Allow it to FULLY CURE. Its low pressure, about 40 psi. Most likely it is R12. Forget finding R12, use R134a. Use piercing valves on the low and high side. When you are ready, use the freon to flush out the air that is in the system. That means putting freon in the low side and have it come out the high side. It must not have anything but freon in the system. You can go to harbor freight and buy a
cheap vacuum that uses your air
compressor to get a vacuum. Not the best but it will
work. Add R134a until you see about 35 to 36 degrees on the pressure guage. DO NOT START THE
COMPRESSOR IN A VACUUM. Is this a professional fix? No. But it will
work but there is no guarantee how long it will last. If you are a weekend crusier ok. I wouldnt use it and go on a long voyage. This is a fix within the mans abilities. Being a professional ac tech I strongly say there is no guarantee for this fix but hey what have you got to lose. A few dollars a little time, if it doesnt last call someone like me or go buy a new one.
From the Redneck Nerd.