I reused my line set because it was in a wall. The outside condenser and a coil were replaced but the old line sets were not cleaned. There may be a mix of r22 and 410a in my new system. Can the system be flushed completely. I was going to replace the A coil and try flushing the compressor and line set. Will this work?

Not a chance of getting that POE oil cleaned of any traces of mineral oil.

All you can do is hope there wasn't any of the old oil left in the lineset at this point.