[bob deluke]

A couple simple things to check with the contractor. Is the vacuum pump a minimum 3-5 CFM capacity? Is pump oil clean, should be changed after each use as contaminates, moisture are captured in the oil. Does pump pull below 500 microns when “blocked” off? Does the tech know triple sweep, double evacuation procedure? Did they purge the line set with nitrogen before brazing to prevent oxidation? Looks like they used foscopper brazing solder on the lines, not silver solder or silfos or stabrite. You should talk to the tech intelligently before he starts to work as rwest suggests, so he knows you’re pretty well versed as to what’s happening with the system. Good luck, hopefully the problem will be resolved.