To give a little history, this is a Goodman 5 ton heat pump 15 or 16 seer, can't remember which. Installed 4 years ago and have not had one heating season without problems. One year in service and the compression goes out and had to be replaced along with thx valve. 6 month later reversing valve gets stuck in cooling. Valve taken out and replaced with whole dryer assemble, only thing left was the compressor. 8 weeks later new reversing valve gets stuck in between heat and cooling mode. Added Zerol Ice to help free valve. With a little work of banging and switching the valve from heat and cooling many times, the valve does switch but sluggishly. It will take about 5 minutes once the compressor turns on to fully switch into heating and the same with cooling. For that 5 minutes, the compressor is a little noisey and little to no refrigerant is moving. I have had a local Goodman installer do the repairs from day one but I think maybe the proper procedures where not followed. What should I expect from the tech that replaces it again. I read that there should be a Nitrogen purge placed on the unit during brazing. I know for a fact that was not done for the compressor nor the reversing valve. Should a sweep of the system be done with R22 before another reversing valve is put back in? Any help would be appreciated.