A/C and Heating System Components Guide

A/C and Heating System Components Guide

A/C and Heating System Components Guide

Most people don’t know very much about how their air conditioning and heating systems work. That’s part of the reason some HVAC companies have a reputation for overcharging and recommending unnecessary services. We always recommend that our customers learn some of the basics about their heater and air conditioner. This will help you diagnose problems more quickly, take part in your own AC maintenance, and avoid getting overcharged by any HVAC contractors who don’t have your best interests at heart.

An efficient HVAC system is absolutely critical here in the Phoenix area, especially when summer temperatures start to climb over 100°F. Learn more about the different system components, how they work, and what you can do to keep up with your AC maintenance. Once you understand the critical components on the following list, you’ll be able to prevent expensive repairs, maximize efficiency to reduce utility bills and make informed decisions about your Phoenix HVAC services.



The thermostat is the component most people understand the best, which makes it an accessible place to start your understanding of the HVAC unit. As you probably know, the thermostat has an input where you can set your desired temperature, and it will communicate with the rest of the heating and air conditioning components to get your house to that temperature. So, exactly how does the thermostat work?

Your thermostat has at least one temperature sensor that will measure the current temperature in your home. Some modern thermostats even have additional sensors you can place around the home to get a more comprehensive reading. The best places for these sensors include rooms where you spend a lot of time, and they should be away from windows, walls, drafts, and direct sunlight. 

If your heating and air conditioning system has different zones, you can save money on utility bills by setting each area of your home to a temperature that’s appropriate for that area. For example, you can avoid treating rooms where no one ever goes. Many people also like to turn off the system for all rooms except for occupied bedrooms at night. If you have a smart thermostat, you can set a schedule or control it remotely to save money while you’re out of the home.

The sensors and the thermostat controls send signals to your HVAC unit via wires, which makes the thermostat your control center. When the temperature becomes too hot or too cold according to your setting, the thermostat will sense that. It sends a signal to engage your heating or cooling until the temperature in your home gets back to the appropriate level.


Furnace and Indoor Air Handler Vs. Outdoor Unit

The furnace and indoor air handler are the parts of your HVAC system that are inside your home. They’re typically large and require a lot of space. Yours are probably in the basement, attic, or closet that was designed to hold them. They’re connected to electricity, gas, or another energy source like your solar panels. 


Condensing Unit

This is the HVAC component that’s installed on the outside of your home, where it releases heat into the outside air. The condensing unit is connected to the evaporator coil (more on the evaporator coil shortly). The condenser coil or compressor is filled with refrigerant, which it condenses from a gas to a liquid. As this the refrigerant condenses, it undergoes a heat exchange that cools it off. The fan in your outdoor unit blows air over the compressor to create a wind-chill effect that helps the refrigerant cool down even more quickly. 

Once the refrigerant has been cooled down enough to enter a liquid state, a metal tube takes it into your home to the evaporator coil. To keep this process fast and efficient, it’s important for the condensing unit to be clean and clear. With the unit outside, it’s important to make sure it doesn’t get coated with dust or dirt. Make sure there’s empty space around your outdoor unit, and rinse it off if it gets dirty or covered with yard waste. If your condensing unit is in the shade, it will naturally be a little bit cooler and therefore more efficient.


Refrigerant Lines

The metal tubes that carry cooled refrigerant from the condensing unit to the evaporator coil are called refrigerant lines. Once the evaporator coil uses the refrigerant, it’s transferred back to the condensing unit in its warm, gaseous form. These tubes are made out of durable metal like aluminum or copper. It’s important for the refrigerant lines to remain in good shape because holes or other damage can result in refrigerant leaks. If you feel like you always need more refrigerant in your system, it could be because there’s a refrigerant line leak.


Evaporator Coil

The simplest way to understand the evaporator coil is that it does essentially the same thing as the heat exchanger but in reverse. It’s located in the indoor air handler, which is the big part of your HVAC unit inside the home. Refrigerant lines deliver refrigerant to nozzles or valves inside the indoor air handler, and the refrigerant gets dispersed so it can evaporate from a liquid to a gas as quickly as possible. The heat exchange from this evaporation process absorbs heat from your home, lowering the temperature.

While this is happening, your HVAC system blows warm air from the home over the evaporator coil, which cools the air down. It also causes condensation when the air is cooled so quickly, pulling humidity out of your home to make it feel cooler and more comfortable. Once the air is cooled and dried, it’s ready to go back into your home again. The refrigerant eventually heats up, then it gets sent back to your condensing unit to cool down again.

HVAC technicians always check the evaporator coil during routine AC maintenance because the condensation can cause a buildup of excessive moisture. If the moisture isn’t disposed of correctly, it can gather on your coils and lead them to collect dust and dirt more quickly. Dirty evaporator coils can’t work as efficiently, and they’re also more likely to break down. Protect your equipment and air quality by making sure there is no mold, dirt, or ice on the evaporator coil.


Heat Exchanger

The heat exchanger is part of your furnace. It absorbs heat from the combustion in the furnace and uses it to warm the air before your HVAC system carries the warm air through your home. Even electrical furnaces have heat exchangers– those just use electricity-generated heat instead of heat from combustion. Heat exchangers are designed to take in cool air and heat it quickly, and they’re made of temperature-resistant metal to make sure the equipment isn’t damaged in the process.

It’s important to have this component inspected regularly because some heat exchanger problems can be dangerous. A leak could expose you and your housemates to carbon monoxide, which is poisonous. If you have a gas furnace, we recommend having carbon monoxide detectors installed. Carbon monoxide has no color or scent, so people need sensors if they want to know about leaks before they start experiencing symptoms. Between sensors and yearly HVAC inspections, you can have greater peace of mind about your heat exchanger.


Combustion Chamber

The combustion chamber is also known as the burner. This is where furnaces combine air and gas to start the heating cycle. Once there’s some oxygen and other combustible gas in the combustion chamber, it can be ignited with a pilot light or glow stick. The fire starts, then more gas and air are added to help the fire get hotter. The most efficient furnaces even have second combustion chambers. The second combustion chamber will capture the carbon monoxide and unburned fuel from the first combustion chamber then light it again to maximize energy efficiency.

Your furnace won’t be able to start a fire in the combustion chamber if the pilot light has gone out. You or an HVAC professional will have to carefully relight the pilot by following the instructions for your specific HVAC unit. Faulty pilot lights can also release carbon monoxide, which is dangerous. This is part of the reason most modern furnaces use glow sticks, also known as electronic ignition systems. If your furnace has an electronic ignition system, you’ll never have to worry about relighting the pilot.


Blower Motor

The blower motor is what pushes treated air throughout your home after it’s reached the desired temperature. The blower motor provides power for a fan, and that fan forces air out of the HVAC unit and into your ductwork. The blower motor and the fan normally keep going for a little bit even after your system has stopped heating or cooling air to make sure that all of the treated air has had time to go through the ducts and get into your rooms. Once that happens, the motor shuts off until it’s time to push more treated air throughout the home. Some blower motors only have one speed, so they’re either on or off. Newer HVAC systems are more likely to have variable speed blower motors, which can run at different speeds depending on your needs and preferences. Variable-speed blower motors give you greater control over your heating and cooling, and some of these components also include technology to help identify problems in the HVAC system. Since variable-speed blower motors can operate at lower speeds, they can run more continuously instead of stopping and starting while always hitting top speed. This makes the system less noisy, saves energy, and keeps the home’s humidity more consistent.



The vents are some of the most recognizable components of your HVAC system– you probably already know where all of them are in your home. This is where the treated air can enter your home. Some vents can be manually adjusted to direct air to where you want it. We normally recommend that people include their HVAC vents during their regular cleaning and dusting around the house. If your vents get too dirty, they’ll eventually start to reduce air circulation, increasing the strain on your equipment, and rising energy bills in the process. Dirty vents also decrease the air quality in your home since they release dust, pollen, and allergens into the air that’s coming out.



The ductwork in your home is a series of passages for air to go through as it makes its way from the HVAC unit to your vents and into your rooms. The ducts might be made out of steel, plastic, fiberglass, or even other materials like fabric. For the most part, though, ductwork is made out of aluminum. It’s important to have your air ducts cleaned and inspected for a few different reasons:

  • Leaks and blockages can prevent good air circulation and make your system inefficient.
  • Dirty ductwork reduces the air quality in your home by introducing dust, bacteria, and other contaminants into your rooms along with the air. This is especially important for people who have asthma, allergies, or other breathing problems.
  • Damaged or poorly insulated air ducts allow the temperature of your air to change b[efore that air ever makes it out of your vents.


HVAC Services in the Phoenix and surrounding areas.

At Howard Air, we want our customers to understand what we’re doing when we service their HVAC unit. Our technicians are knowledgeable and trustworthy, so we have nothing to hide in our process. When you know a little bit more about your heating and air conditioning, you’ll be able to make more informed decisions about your AC maintenance. We’ll always give you an honest professional opinion about all of your options, and our staff will walk you through every step of your HVAC services. Contact us today for a fast response. We’ll work with you to see how we can save you money and make your home as comfortable as possible.

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