[TheForge] TheForge Digest, Vol 99, Issue 9

[Cindy and James]

4. Re: Soldering copper tubing in an AC unit (Andrew Vida) 5. Re: Mower 
vs boot scraper (Andrew Vida) 6. Re: Mower vs boot scraper (Andrew Vida)

I'm certified in HVACR, but don't work in the field.  However, I'll add 
this to your soldering issue...

Sounds like they guy that worked on your unit needs to be reported to 
the HVACR police and may have ruined your unit.  At any rate, keep this 
guy away!  He sounds quite illegal (literally).

Soft solder will really NOT work in an AC system due to higher 
pressures, vibration, etc.   You need silver solder, generally the 
higher silver content the easier to solder.  When soldering, it helps to 
run a low level of dry nitrogen gas thru the system to keep crud from 
oxidizing inside the coils that will have a detrimental effect on the 
compressor, condenser, evaporator, etc.  You also need to put a DRYER in 
both the liquid and suction lines to catch the crud this guy has caused, 
not to mention having the system open to the air.

You will need to pull a good vacuum and let the vac pump run for a good 
while.  A good micron gauge can be useful to tell you just how good of a 
vacuum you are getting before you recharge the system.  Be sure to test 
for leaks.

  I have soldered a LOT of AC systems w/ Ox/Ac, but use a CARBURIZING 
flame as opposed to an oxidizing flame.  You need the metal to be CLEAN, 
inside and out.  If the guy burned the copper, I really think you need 
to cut that part away and go back to clean copper.  You can swage it to 
fit what size copper you are using if need be.  This can really be a 
bi*ch.  Take your time and do it right.

James
Paris, Texas