Performed preventative maintenance for two air conditioning systems. One system is in the basement and one is in the attic with pull down steps. Replaced the standard air filter for the basement system. Replaced the Merv 11 air filter for the attic system (20x25x5). Inspected all the electrical components. Confirmed proper high and low voltages. Tested the amp draw of the blowers, compressors and fan motors. All were operating within the manufacturer specs. Tested the temperature split between the supply and return. The basement system was operating at a 19° differential and the attic system operating at a 20° differential. Made sure to test the drain for the attic system since it’s has issues in the past. Ran a jug of water through the piping to make sure no clogs in the pipe. Water drained without issue during testing. Both systems are operating properly at this time.