A staple in just about every home, an air conditioner is far less complex than normally thought. Air conditioners work by drawing in the air around it, cooling it, and then distributing it throughout its duct system. This is true of home air conditioners, car air conditioners, and even refrigerators.
If you want a better understanding of your air conditioner, you must learn the basic components and what they do. Think of the inside of the air conditioning unit as a square containing a circuit with four major parts: The compressor, the condenser, the metering device, and the evaporator.
What is an Air Conditioning Compressor?
The compressor is often thought of as the heart of an air conditioning system. It is what takes in the gas refrigerant at a low pressure and temperature. Then the gas is literally compressed to give it a high pressure and high temperature. This hot gas is then sent via a discharge line to:
What is an Air Conditioning Condenser?
The condenser is at times called the condenser coil because of its coiled shape. Its function is to take in the pressurized, hot refrigerant and absorb and release its heat outdoors in order to cool it, which is why you can often feel hot air coming from your air conditioning unit. The process remarkably cools the gas and turns it back into a liquid. This liquid then flows down the liquid line and through a filter drier specifically designed to catch contaminants and keep them from flowing into the rest of the system. This newly cooled refrigerant is then sent via the same line to:
What is an Air Conditioning Metering Device?
The metering device is what divides the high and low-pressure sides of the air conditioning system. The device is designed to maintain a specific flow rate of refrigerant into the low side of the system, or the side that sends cool air into your home. The metering device also drops the psi of the refrigerant as well as lowers its temperature. It then sends the refrigerant via the same liquid line to:
What is an Air Conditioning Evaporator?
Similar to the condenser and its coil system, the evaporator takes in the refrigerant and works it through a system of coils. The refrigerant enters through a small opening called an expansion valve that works similarly to the nozzle of a can of aerosol. It then travels down the coils, which further absorb any heat it contains before blowing the newly cool air through the ductwork with the use of a fan. The leftovers are then sent back to the compressor through a suction line to have the process repeated.
How is Air Cooled With an Air Conditioner?
Now that you know the parts of your air conditioner, it’s time to learn about the process and chemicals in which the air in your home is cooled.
The most complex part of the process is the cooling. This is accomplished not by cooling the air as commonly thought but by removing the heat from existing air through the use of refrigerants. One of the most common is Freon™, which was developed by the DuPont company. It is part of scientific family of gases known as chlorofluorocarbons or CFCs. Prior to Freon, ammonia and related substances were used to cool air but were found to be toxic. CFC’s became the norm after, although there are those who suspect it of damaging the Earth’s ozone. While newer air conditioning units can operate with a variety of substances, older units may only work with Freon. After Freon came R-22, which was the designated refrigerant on units manufactured from the early nineties through 2005. New units manufactured in the last few years use a completely synthetic refrigerant designated R-410. The changes in refrigerant present problems for homeowners because they are not compatible with each other. If you have an R-22 unit and the evaporator dies, you may have to replace the evaporator and condenser due to compatibility issues.
What About the Other Parts of an Air Conditioner?
In addition to the four main components, there are many other secondary components to an air conditioning system.
Air conditioner lines – As explained above, the lines connecting the components of an air conditioner to each other are a vital part of the system. They include the discharge line (line running from the compressor to the condenser), the liquid line (line running from condenser to the evaporator), and the suction line (the line running from the evaporator all the way back to the compressor).
Refrigerator/Freon pipe system – Also known as the liquid line(s) running from condenser to the evaporator, these are commonly the lines that experience problems, especially in outdoor units. This line can also be split into pairs, with the larger pipe transferring the gas and the smaller carrying the liquid. The larger gas pipe is also often insulated to both increase efficiency in the cooling process and prevent condensation on the pipe. Damage, wear, and leakage can happen on these lines and most often in the spot where the pipes pass through the wall of the home if it has an outdoor unit. One of the most prominent signs of damage to these lines includes oil deposits which are caused by leaking refrigerant.
Condensate fluid drains – The air conditioning process causes water vapor and condensation, resulting into dripping water, which is called condensate. It then drops into a primary condensate drain pipe which will usually be connected to the plumbing waste piping in the attic or under a nearby bath sink (depending on year of construction). If the primary drain system fails, a pan is installed under the evaporator to act as a “back-up”. Build up in the condensate drain pan can cause the water to back up and spill into the home. This is more common at the beginning of spring when the cooling system has been idle for a few months and in humid, southern climates. Blockage in the primary drain line can be repaired or simple maintenance can be performed by removing the cap on the drain line access (if your unit has one) and pouring warm water and/or a cup of bleach through the line.
Some other facts to remember about modern air conditioning:
- In outdoor air conditioning units found in homes, the compressor and condenser are normally found on the outside units, with the indoor containing the evaporator and its components.
- One of the best ways to maintain an air conditioner is to regularly replace the filter(s). They are commonly rectangle shaped and are found in the furnace, ceiling, floor, or wall covered by a slotted metal door. A good tip is to write the current date on your new filter so you know how long it has been in there.
- Keep the batteries in your thermostat fresh. Even though your thermostat is connected to your air conditioning unit by a host of wires, the batteries are what actually power your thermostat. Low thermostat batteries can cause your unit to do more work than it has to and are easy to replace.
- If you have refrigerant/Freon pipe systems running from outside to inside, be sure that the pipes are not touching and are protected by sleeved openings. The larger refrigerant line should also be fully insulated from the condenser to the evaporator. Having an HVAC technician install a sleeve can save far more money than what it costs to have installed by preventing damage and improving efficiency.
- Have your AC serviced by a licensed or certified technician each spring. The $75.00 that you spend to conduct basic annual maintenance can add 50% to the life expectancy of your system.
- Do not attempt to add Freon or other refrigerants to your air conditioning unit. Techs need to be EPA certified and can also tell you what type of refrigerant is best for your system, whether it’s R-22, R-410, etc.