Does anyone know a reputable shop that can service the AC system in my W126? I live in San Pedro, CA. It doesnt blow cold intermittently. Apparently the previous owner had part of the system's plumbing converted to R134, but not all of it. That is the story from my current shop. Is it possible to have both R12 and R134 plumbing and still have an operational system? If so, could that be the reason my AC blows cold often but fails to blow cold sometimes? Thanks in advance for any advice