Air handlers and furnaces aren't often used together in Oklahoma City. If you use a furnace, you most likely won’t need to spend time thinking about an air handler.
Air handlers are typically linked with heat pumps and manage airflow throughout your home. Some models also offer secondary heating and cooling pieces to assist the heat pump.
A furnace heats in a different way by blowing hot air into your vents, which circulate it across your residence. Because furnaces use combustion chambers to produce hot air, they don't use some of the parts you'll see in a standard air handler.