Goodman heat pump about 2 months old. Works great and house is warm. I charged during warm weather using sub cooling method. In cold weather frost pattern is even. Problem is a loud compressor noise for about 5 sec. when ever the reversing valve switches direction, and then again when it comes out of defrost. It sounds like liquid being sucked into compressor. It has a scroll compressor. It doesn't make the noise when put into A/C by the thermostat. I don't think it is overcharged judging by the frost pattern, and shouldn't the accumulator prevent any liquid from entering comp? Anyone have any ideas on this, or is it just the nature of the beast?