Evaporator Coil
An evaporator coil is located in the indoor unit, close to the blower—the refrigerant cycles through it. The refrigerant is cold while it’s in the evaporator coil. It absorbs heat from your home’s air. The cooled air is then blown into the ducts. The warm refrigerant continues through the closed-loop system to the outdoor unit, where it can release the heat energy from your home’s air.
Condensate Drain Pan and Line
When air passes over the evaporator coil, it cools. Cooler air can’t hold as much moisture as warmer air, so some of your home’s humidity condenses into water. That water collects in the air handler’s drain pan. The drain pan connects to a PVC pipe called the condensate line. The condensate line connects to your home’s wastewater drainage system.
Compressor
Once the refrigerant absorbs heat from your home’s air, it turns into a gas. The gas is warm but not warm enough to release enough heat energy to the outdoor air. The compressor adds pressure to the gas. This makes the refrigerant get even hotter. At this point, the refrigerant is hot enough to cycle into the condenser coil and release its heat.
Condenser Coil
The condenser coil is located in the outdoor unit. The superheated refrigerant passes through it. The condenser’s fan pushes outdoor air across the coil. This facilitates the release of heat from the refrigerant. The condenser’s coil is prone to debris buildup from dirt, dust, pollen, leaves, and grass. It’s contained within a housing. The housing is made of powder-coated or stainless steel, and the unit is typically placed on a concrete platform or a rooftop. It has fins that help air circulation and heat dissipation. This housing needs regular cleaning. We typically do this during an annual maintenance visit. We recommend trimming all vegetation at least three feet away from the outdoor unit. This protects the condenser coil, fan, motor, and fins.
Expansion Valve
The expansion valve reduces the pressure of the warm liquid refrigerant after it passes through the condenser coil. The low-pressure liquid gets cold after it passes through the valve. Most air conditioners have an internally equalized expansion valve. The valve also has a pressure sensor that triggers its functions and maintains the right pressure for the refrigerant. Once the refrigerant is cooled again, this completes one cooling cycle. The refrigerant is ready to enter the evaporator coil again and absorb more heat from your home’s air.
Refrigerant
The refrigerant is a man-made chemical. It’s engineered to absorb heat energy—refrigerants cycle between a liquid phase and a gas or vapor phase. If your air conditioner is more than 10 years old, it probably uses Freon as its refrigerant. Also called R-22 by heating and air conditioning technicians, Freon has been phased out of use. This is because it causes damage to the Earth’s ozone layer. If your air conditioner was made in 2015 or later, it uses a new, environmentally friendly refrigerant called R-410A. This refrigerant doesn’t cause harm to the ozone layer. R-410A can’t be used in an older air conditioner designed for Freon. If your old air conditioner develops a refrigerant leak, it’s best to replace it with a new cooling system with R-410A.
Air Handler
The air conditioner’s air handler is part of the indoor unit. It contains the evaporator coil, air filter, blower motor, and several electrical components to regulate airflow. It’s contained in sheet metal. The air handler also connects to your home’s air duct system.
Air Filter
The air conditioner’s filter is located in the air handler. Its center area may be made of fiberglass, cellulose, or similar fibers. The fibers are layered in different directions. A cardboard, particleboard, or aluminum frame holds the fiber layers in place. These fibers trap debris from your home’s air. Filters are rated with the Department of Energy’s minimum efficiency reported value (MERV) rating system. MERV ratings range from one to 20. The higher the MERV rating, the greater the number of tiny particles the filter traps and removes from your home’s air.
Fan
The air conditioner has two fans. One fan is located in the air handler. It’s responsible for blowing the cooled air into your home’s ducts. The air is blown over the evaporator coil, where it cools. Moisture from the air condenses into water, which is drained away through the condensate line. The cool air passes through the air filter, which traps particles. Finally, the air enters your ducts, passes through the vents, and reaches your home’s living space. The second fan is in the outdoor portion of the air conditioner. It dissipates the heat from the condenser coil. This fan’s blades are prone to damage from debris falling into the outdoor unit. They can also get pollen, dirt, and dust buildup, which is why keeping up with air conditioning maintenance is so important.
