On downstairs system, tech found braze joint that connects liquid line to air handler leaking. Tech recovered 1.5 lbs of remaining refrigerant and flowed nitrogen while fixing braze joint and replaced biflow filter drier. System passed positive pressure test and standing vacuum test at 260 microns. Tech recharged with 8 lbs 5 oz of new R410a plus no additional refrigerant for short lineset. Tested system without issues. Downstairs system is back operating correctly. Install warranty. Mr Crumpler reported upstairs system is working properly. During repairs, upstairs system cycled on and off regularly. Upstairs thermostat is maintaining 70 degrees.