I have been working on a reach in freezer on a that has a MOP expansion valve. I am have trouble with the compressor starting and staying online when coming out of defrost. My thought is it needs a CPR valve, but I know you can't have both devices on the same unit. The expansion valve has been recently changed so I think is doing what it is designed to do. Would it be advisable to change to a regular expansion valve and add a CPR valve?