Sorry to say this, but you are WAY off base here in several ways. A/C hoses typically use O-rings or crush washers, but not any sealant on the threads. Unless of course there is something different about the newer cars, but that is not likely; my experience is with older cars (typically pre-90). Someone please correct me if I am wrong & need to be educated about this .

You also do not simply replace a line that was broken a year ago, charge it up, and go happily down the road. Check the search function here for more information regarding replacement of the receiver-dryer, vacuuming the system to remove moisture, etc..