Why is my AC unit turning on and off frequently?  Pippin Brothers, Lawton, OK
March 13, 2012

One of the most popular types of central heating and cooling in Oklahoma are split systems. Most likely, you have a split system in your home without even realizing it. It’s called a split system because the components of the system are split, containing an outdoor air conditioning unit and an indoor coil (usually installed on top of your furnace). 

This quick walk-through of the parts of a split system will give you a better understanding of what’s going on the next time your air conditioner or furnace turns on.


Every heating and cooling system has a thermostat. It monitors the temperature of the home and tells the rest of the system when to turn on and off, based on your input.

Return Duct

When the system turns on, the fan or blower is engaged, causing the return duct to extract air from your home and bring it to the heater or air conditioner.


Also called grills, registers are the visible parts at the end of your ductwork. They have directional pieces that are designed to evenly distribute the air throughout your rooms.

Indoor Coil

In a split-system, this is the indoor part of your air conditioner and is usually located above or adjacent to your furnace. Warm air is blown over the cool indoor coil, which absorbs the heat from the air and transfers it outside, thereby cooling the air.

Air conditioner

The air conditioner in a split system is located outside and contains the compressor, condenser unit, fan and other parts that help cool your home by removing the heat from the air in your home.

Heat Exchanger

The heat exchanger is part of your furnace. Heat is transferred from the furnace to the air as it passes through the heat exchanger.


The furnace is the large indoor “box” that contains components that turn oil, gas or electricity into heat. Some of its important components include, a blower, burners, combustion chamber and heat exchanger. 

Air Ducts

The air ducts, or ductwork, in your home carry and distribute the heated and cooled air through your home. These most commonly consist of flexible ductwork or sheet metal.

This is only a small introduction to the vast array of parts that make up your central heating and air conditioning system, but it should help you be able to identify most of your system’s key components. 

Pippin Brothers is a complete heating and cooling contractor serving the greater Lawton, Oklahoma area. If you have a question, don’t hesitate to ask our expert.