If the R134A can hose went onto the connectors then your AC system has been converted at some point...or rather someone may have bought the R134A adapters and did a no-no and mixed the refrigerants, seen this a few times with the cheap ass people in town where I live. I bought the stuff and converted mine myself at home, and have been happy about saving myself about $1800. I had to buy a replacement AC Compressor, vacuum pump, and AC gauges but I now have the equipment to do the work whenever I need to. I also took the time to get my 609 certification so I can legally do the work, it was only $20.