Originally posted by billva
any time a system is opened to the atmosphere it needs to be evacuated of non condensibles and a filter/drier installed.
You have to be careful of this statement. When it comes to a fresh install anyway. Many brands have a liquid line filter dryer installed inside the unit and it would be bad to add a second one in-line. I've been jumped by people over this before and had to shoe them the dryer inside the unit. One time this happened and they still didb;t believe me after seeing it because it was one of the small copper exterior dryers and they didn't know what they were looking at. I had to have Trane fax them that yes this is a dryer and no another one is not required. On the flip side, when performing service/repair work and I open up the system I remove that factory dryer and install a new one. Most shops in my area don't even know it's there and just throw on a second dryer. Can you say flaming compressor death?