Completed two system, furnace, maintenance and inspection. I cleaned flame sensors and wiped down furnaces. I tested components and amp draws. I checked air pressure and temp splits. The air filter on the north side of the house needs changed out. Neither of the two humidifiers on the systems are connected. They are both from the 1980s or 1990s. One of the humidifiers has bacterial growth inside of it. In order to supply more humidity to the building, the humidifiers would have to be replaced. Blower wheels are developing dust. Once it builds up enough, we will need to Pull and clean out the blower wheels. Both furnaces are operational at departure.