To have the warrenty valid you need to put in a new dryer/ receiver. Then you can put in R134.

The the change was made from R12 to R134 there was talk about not being able to mix the 2 refrigerants but I have found that to be not true.

When you changed the compressor you lost all the refrigerant charge so the recovery part is a non issue.

Find out what the factory charge is and put the exact amount back in, more is not better.

Refrigerant being bad for the ozone is one of the biggest lies Al Gore ever pulled off,it's heavier than air,
now it's the CO2 lie.
Remember he tried to take credit of "Inventing the Internet"