I just noticed a pile of junk air conditioner outdoor units all have valves that are used to seal the system for charging. I think they should work with high pressure, low pressure. On 02/11/2015 7:59 AM, "John Gardner" wrote: > I'd suggest (again) that you peruse "The Amateur Scientist" > > columns in 1950s issues of "Scientific American" magazine. > -- > http://www.piclist.com/techref/piclist PIC/SX FAQ & list archive > View/change your membership options at > http://mailman.mit.edu/mailman/listinfo/piclist > --=20 http://www.piclist.com/techref/piclist PIC/SX FAQ & list archive View/change your membership options at http://mailman.mit.edu/mailman/listinfo/piclist .