Popgadget
Elite Member
watched several videos on taking sub cooling readings on AC unit, since mine use TXV valve. nameplate does not list expected value though.
Finally just decided to call a guy to come look at it. downstairs unit starting to freeze the evap coil.
There is usually a chart either in the units documentation or on a sticker inside, the sub cooling value is dependent on inside temp (dry and wet bulb for RH) and outside temp. Absent the chart, there are apps that can provide a generic value. Having a sight glass on the liquid line leaving the condenser is a big help for quick evaluation.
A frozen evaporator is indicative of low refrigerant or low airflow. Make sure all returns are open and not blocked and the filter is clean.
Having a tradesman look at it isn’t a bad plan, but keep those things in mind as you watch him troubleshoot it to verify.