Came out to call. Customer stated that the upstairs system was freezing up and wasn’t cooling properly last week. They changed the filters Thursday to see if that would change it, and it started freezing up again on Friday. I cycled upstairs unit and checked operations. System was functioning properly, but I noticed my suction pressure and temperatures were dropping after about 15-20 minutes of run time. I started checking line temperatures in different places and found that the liquid line drier in attic was reading 85.8 on one side and 83.4 on the other and kept fluctuating a degree or so. I discussed with customer about what I found and recommended. I’m coming back tomorrow to change out the filter drier and recheck system operations. Came back out to call to change out filter drier. I pumped down the AC system. Took out the old filter drier, and brazed in new drier on existing lineset. Checked welds, then pressure tested lineset and coil using nitrogen. After the positive pres