Although air conditioners differ from model to model, they all operate on common principles. In this brief article, we cover how central air conditioners work (as well as potential problems you may experience).
Included among the major parts that comprise a central air system, the condensing unit (installed outside of your home) contains
- air conditioner condenser coil
- a compressor, and
- a condenser fan motor
Inside the house, the evaporator coils (or cooling coils) are mounted atop a furnace or air handler. The furnace or air handler uses a circulation blower fan to pull air through the returned vent, blow it past the evaporator coils, and force the air through the home. The room air is then pulled back through the cold air returns and the cooling cycle continues.
Once the room air has cooled sufficiently, the wall thermostat signals the circulation blower fan and condensing unit to shut off, until the room temperature rises.
This process can be broken down into three main sections
- temperature control
- air circulation
Temperature Control: the Thermostat
The temperature in the home is regulated by the wall thermostat, which must be located in a central location in the house, positioned at eye level, and away from direct sunlight for proper temperature regulation. The thermostat can be powered by electric from the furnace control board or by internal batteries.
When the thermostat detects an increase in temperature, it closes the cooling circuit, allowing voltage to travel to the control board. The control board uses a time sequence to send 120 volts of alternating current to the circulation blower fan motor in the furnace, and 24 volts to the condensing unit contactor. It allows 240 volts to flow through a nearby disconnect box to the compressor and condenser fan motor when the condensing unit contactor is energized.
The disconnect box, which offers a way to turn off power to the condensing unit outside, includes a cartridge which may contain fuses. If the compressor and condenser fan motor fail to work, the cut off box fuses can be tested for continuity to determine if a continuous electrical path is present.
The system’s compressor is a pump, converting refrigerant in gas form into the condenser coils, where the gas is condensed into a hot liquid. The condenser coils dissipate the heat as the liquid travels through them, and a fan is used to assist the coils in this process.
Once the refrigerant travels through the condenser coils, it moves to the evaporator coils located on the furnace or air handler. As the refrigerant liquid enters the coils, it expands into a gas, which makes the coils cold. The gas moves through the coils to a suction line connected to the compressor. The compressor converts the gas back into a liquid and the cooling cycle repeats.
The humidity in the air condenses on the cold evaporator coils and drips down into a set of collection trays. The trays are affixed to either a condensate pump or a floor drain. It is vital to keep the condenser clear. If not, the heat will not be dissipated properly and the system will not function efficiently.
Typically leaves or other particles can clog the coils. You can use a regular garden hose to clean the condenser by spraying the coils from the inside.
Air Circulation or Airflow
The most important aspect of efficient operation of the air conditioning system is air flow. To ensure proper air flow, the air filter should be checked monthly and serviced as needed.
There are several types of filters installed in a typical HVAC system, and can range from one to five inches thick. The filter can be installed into the slot in the return or in an air cleaner. Some homes are equipped with an electronic air filter which is powered by the furnace or air handler control board.
When the circulation blower fan activates, the blower fan motor can run at multiple speeds to improve efficiency. When the furnace is heating and higher speeds (1220 CFM) are used for air conditioning, lower speeds (750 CFM) are used.
If the circulation blower fan becomes noisy during use, the set screw on the blower wheel may have loosened, causing the wheel to wobble on the motor shaft. You can fix this problem by tightening or replacing the screw, or replacing the blower wheel altogether.
Our Annual AC Tune-Up and Checkout Service
We recommend having your AC system checked out once a year to ensure most efficient operation. We’ll catch little problems before they become big ones, saving you money and troubles. An added bonus is you’ll save energy because your system will run more efficiently.
When it’s time to schedule routine maintenance for your home’s AC system, or your system isn’t cooling as effectively as it should, call Groveport’s best HVAC contractor by phone at (614) 861-5203 or schedule a visit using our Schedule Now page.