Personally I always use a dryer when changing a compressor or condensing unit but as I'm sure many of you have noticed not everyone does. It seems to me that I find more compressors that dont have dryers installed go bad than compressors that had dryers intstalled. But I have no real proof of it. I have seen systems that are quite old and dont have dryers installed and they are working just fine. Does anyone know of any conclusive proof that a dryer increases compressor life? I've wondered does it double the life, just add a little extra life or does anyone really know?
I also assume that if I see a unit without a dryer there is a pretty good chance a vacuum wan't pulled either.