https://youtu.be/uyZWxWm4QCo

I have been struggling with AC issues, doing a little research, and
stumbled on this. Since Sanden compressors are what most of us have an our
vans, I found this to be most helpful. It also answers my question about
the appropriate oil to use as well. The Sanden website did not explain that
very well, but Sanden was insistant that if the AC is used regularly, the
receiver/dryer should be change out about every 3 years. It seems that no
matter what, some moisture gets in, and that moisture mixed with R134a
makes an acidic mix the can destroy your system from the inside and you
will never know it until too late.

Not said, but suspected, this is at least one of the reasons for EPA
getting rid of R134a next year. I suspect the auto industry backs them up
also.

John