for the $20 certificate, see http://www.macsw.org/imaca.php

"jw" wrote in message
oups.com...
licensing and accreditation to legally be messing with this stuff. I
know
you need a license to buy it, but am not sure what you will need to sell
it.
Perhaps you will just keep it back for your own use. Not a bad idea if
you
have been to a car shop lately and priced AC work. Other common
refrigerants are less expensive, but you would have to read the manual,
or
find out if you can do various refrigerants in YOUR apparatus.

Yes, you do need a license to buy the stuff, but that's a relatively
moot point. You can get a certificate for about $20. There is an
online test that you take to get the cert. I don't have the link off
hand, but it's a pretty basic test. If you can't answer the questions,
you shouldn't be messing with A/C anyways.

It isn't that big of deal to convert most R-12 systems to R-134. And
R-134 is off the shelf. At least in Minnesota. Biggest thing is
flushing the system of the old oil and using R134 compatible ester oil.

JW