When I arrived the unit was not running it was shut down as a result of secondary drain pan overflowing. Found that main drain line from evaporator drain pan was clogged. After blowing out drain line with CO2 a couple of gallons of water poured out of drain line which I documented with a video. Checked air filter, air filter looked brand new. System had 17° split at supply and return. Checked the pressures. Pressures looked good. Tested unit. System operational.