Yes, it would. The oils used in the two refrigerants are different types, and hate each other. Why was it changed in the first place? Flush it, flush it again, check for leaks, and refill with R-12.

__________________
It is a truism that almost any sect, cult, or religion will legislate its creed into law if it acquires the political power to do so. Robert A. Heinlein


09 Jetta TDI
1985 300D