If you are like most people, you have little desire to know the intricacies of how your air conditioner works. When you have a problem, your mind immediately jumps to needing a replacement. Then, the panic starts. This fear is normal, but it’s based on a lack of understanding of your cooling equipment.

Avoid the stress of the unknown, and take a few minutes to learn about your system. You can easily grasp how it operates, what the major components do, and what it may look like when they fail.

Understanding How an Air Conditioner Works

To begin with, it is important to understand the mechanics behind how your system functions. Even if it seems like magic, it’s just a matter of well-applied physics. The system works by circulating air and regulating the pressure of the refrigerant.

You probably recognize the need to circulate air through the system. It draws air in, cools it down, then pushes it back out into the house. The way it cools the air down is by the use of a refrigerant.

However, the refrigerant does not actually add cooling to your air. Instead, it absorbs heat from it. Once the heat is absorbed, it’s then transported outside and transferred to the air there. This is accomplished by the system changing the pressure of the refrigerant. When the pressure increases, so does the temperature. Likewise, when the pressure drops, the temperature does as well. You will see how this applies as we look at the components of the system.

What Are Common Symptoms of a Problem?

Each component in your system may have specific symptoms when it fails. However, there are several symptoms that are difficult for the amateur to trace. They do, however, indicate a problem you need to address before it causes catastrophic damage.

These common symptoms include:

  • Reduced air flow
  • Mounting energy costs
  • Warm air from your vents
  • New signs of moisture around your home


Your compressor sits outside your home in the condensing unit. Its job is to increase the pressure of the refrigerant coming from your home. This pressure increase allows the refrigerant to more effectively transfer the heat to the air outside.

Since it creates a high pressure, the compressor is one of the most strained parts of your system. This means that it will break down over time and need to be replaced. Aside from the common symptoms, you may hear a growling or screeching sound from your condensing unit when the compressor is going bad. It may also trip the circuit breaker for the air conditioner.

When this happens, you’ll probably have to replace the condensing unit outside. In this situation, you may want to replace your entire air conditioner. Your repair technician will help you consider the age and condition of your system to determine the best course of action.

Condensing Coil

The condensing coil is next in line after the compressor. The pressurized refrigerant runs into this set of tubes and transfers the heat to the outside air flowing through the coil. The coil must be hotter than the outside air in order to work well, which is why the pressure is so high.

The condensing coil sits around the outside wall of the condensing unit. It has shielding around it to protect it, but it can be damaged by storms and debris. If the coil is damaged, it is likely more cost-effective to replace the entire condensing unit. The design of the unit makes it exceptionally labor-intensive to try to repair or replace the coil alone.

There are two common problems people experience with condensing coils. The first is an airflow restriction preventing the outside air from flowing through the coil. This is a simple fix and relatively inexpensive. You just need to gently wash the exterior of the condensing unit.

The second problem is more serious, and that is a refrigerant leak. If you hear a screaming sound coming from your condensing unit, this is likely the culprit. Turn off your air conditioner and call for a repair technician.

Condensing Fan

The condensing fan is another critical component of the condensing unit. It draws air from outside through the condensing coil and then vents the heated air out the top. Without this fan functioning properly, your system will fail to work and cool your house.

A very common problem with the condensing fan is blades that are coming loose. This may result in a rattling or whirring sound. However, the fan motor may also give out. This will generally give off a grinding, screeching or buzzing sound. You may also notice that the fan is either not running or it’s turning more slowly than it should.

Evaporator Coil

Once the refrigerant travels inside your home, it goes to the evaporator coil. This is much like the condensing coil, except it is cold instead of hot. The refrigerant pressure drops, drawing down the temperature of the refrigerant in the coil.

Because there is so much air that moves through this coil, it tends to collect contaminants that get past the air filter. This will cause the air coming through your system to decrease, and you will notice that less of it is moving through your vents. This part should be cleaned during your seasonal maintenance to reduce the risk of a restriction.

A refrigerant leak is also a risk with the evaporator coil. Just like the condensing coil, a screaming sound coming from your inside unit is indicative of a leak. Shut down your AC, and open a few windows if you can. The refrigerant in your air can be hazardous to the occupants of the house. Then, call for a repair technician.

Blower Fan

Last, but certainly not least, a major component is your blower fan, also called a circulating fan. This is the fan that draws air from inside your home into your system, pulls it through the filter, pushes it through the evaporator coil, and then back out into your home.

This fan is notorious for collecting contaminants, not to mention for going out of balance. In more serious cases, the blower motor can burn out, needing to be replaced. Usually, these problems are accompanied by sounds like rattling, screeching, or buzzing.

Your blower motor should be a key area of focus during seasonal maintenance. The technician will clean the fan wheel, lubricate the bearings and balance the device. They will also check to make sure the mounting bolts or screws are still tight and secure.

Minor Parts Matter Too

Your system has several minor parts you may hear about during a service call. The most common is the contactor and capacitor in your condensing unit. Both of these are fairly easy fixes for a professional, and they’re relatively inexpensive compared to the major components.

The contactor acts as the switch at the condensing unit, turning the compressor on and off. When it begins to fail, you may notice a chattering noise.

The capacitor holds a large electrical charge to jump-start the compressor. If this fails, you will likely hear a loud buzzing or humming sound.

Regular maintenance helps your air conditioner operate at peak efficiency by inspecting each of these parts. Huft Home Services has been Sacramento’s award-winning AC maintenance, repair and installation company since 2004. Our NATE-certified technicians perform the same range of services for furnaces as well. Our company even provides expert plumbing services to keep you comfortable in your home. Give us a call today to schedule a maintenance visit from one of our extraordinary professionals.

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