Wished they all looked like this!

Check condensate lines and terminations to assure they are clear; also check condensate pumps. If gas check to assure that ventilation has not been blocked, where required, and check to see if carbon monoxide detectors are in place. If not, note the need for these detectors. For water source units check for visible leaks in piping. For all units assure that filters are accessible and are in place.