Components of a Central Air Conditioner

If you’re like most homeowners, you probably haven’t given much thought to how your central air conditioner works. As long as it helps your home beat the summertime heat by providing cool, conditioned air, chances are you’re not interested in how it achieves that goal — at least until it breaks down suddenly.

Most people see their central air conditioners as overly complex devices that only a seasoned HVAC technician can understand. In reality, the average air conditioner can be broken down into four main components: the evaporator coil, compressor, condenser coil, and expansion valve. Each component plays a unique role in helping your central air conditioner provide cooling comfort for your home.

Central Air Conditioner Parts

Read on to learn more about these components and how they help your central air conditioner achieve efficient cooling comfort in your home.

1. The Evaporator Coil

Tucked away inside of your central air conditioner’s air handler, the evaporator coil plays a starring role in keeping your home cool and comfortable. Lined with thin aluminum fins, the evaporator coil looks and functions almost like a car’s radiator except that it absorbs heat instead of rejecting it.

As cold refrigerant enters the evaporator coil, it also draws latent heat from the air passing through the coil. The capture of this heat energy transforms the refrigerant from a cold mist to a warm vapor. Meanwhile, the air that passes through the evaporator coil loses its warmth and moisture, resulting in the cool, dry air that’s fed throughout your home via the ductwork.

Evaporator coils are mostly shielded from dust and debris thanks to the HVAC air filter. Nevertheless, an evaporator coil usually needs a yearly cleaning to prevent cumulative dust and debris buildup from affecting its performance. Given how easy it is to damage the evaporator coil, it’s important that you hire a professional to perform this cleaning for you.

2. The Compressor

The compressor lies at the heart of your central air conditioner. Without it, keeping your home cool and comfortable would be an impossible task. You can find your central air conditioner’s compressor in the outdoor cabinet alongside the condenser coil.

Just as the name implies, the compressor takes in the warm refrigerant vapor and compresses it into a denser form. This process also causes an increase in temperature and pressure, making the refrigerant hotter than before. The pressurized refrigerant is eventually pushed through the condenser coil.

HVAC compressors come in a variety of sizes and types according to your central air conditioner’s rated cooling capacity. However, all compressors rely on a steady supply of refrigerant and lubricant to function properly. Refrigerant leaks can lead to compressor damage, which is why you should have your HVAC technician check your central air conditioner for leaks on a regular basis.

3. The Condenser Coil

Just like the evaporator coil, the condenser coil also plays an important role in your central air conditioner’s operation. Unlike the evaporator coil, however, the condenser coil’s job is to release heat from the refrigerant. Think of your car’s radiator and how it’s designed to help dissipate heat from the coolant circulating inside.

In fact, the way the condenser coil operates is pretty similar to how the evaporator coil works. A condenser fan built into the outdoor cabinet directs ambient air through the condenser coil — similar to how the indoor air handler’s built-in fan directs air through the condenser coil. But instead of absorbing latent heat, the condenser coil uses the air flow to expel heat from the refrigerant.

This process changes the refrigerant from hot, high-pressure vapor into a hot liquid. Before the refrigerant can be reused in the refrigerant cycle, there’s one more important component it must go through.

4. The Expansion Valve

There’s not much your central air conditioner can do with refrigerant that’s in liquid form. In its current form, it won’t be able to absorb latent heat as it circulates through the evaporator coil. In order to complete the air conditioning process, the refrigerant needs to be transformed back into a cold mist. This is where the expansion valve comes into play.

The expansion valve essentially converts the flow of liquid refrigerant back into vapor form. The liquid refrigerant enters the valve through an extremely narrow orifice designed to meter the amount of refrigerant that passes through. A temperature-sensing bulb helps modulate the refrigerant flow based on temperatures within the suction line.

As the liquid refrigerant passes through the orifice, the refrigerant experiences a significant reduction in pressure. The resulting drop in pressure also causes the refrigerant to expand into a mist form. The rapid expansion also throws off a great deal of heat energy, rapidly cooling the refrigerant in the process. The end result is refrigerant that’s returned back to its cold mist form in preparation for its trip through the evaporator coil.

To learn more about your central air conditioner’s components, contact us at Advanced Heating & Cooling today.


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