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Breaking Down the Components of an Air Conditioning Unit

By Aztil –

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How does an air conditioner work? While you may be familiar with air conditioners, most people don’t know the secret behind how ACs “create cold” and effectively cool your house. This lies in how the components of an air conditioning unit work together with the coolant fluid in a constant cycle of compression and expansion.

Air conditioners don’t create cold, they remove heat and the cold exists without heat. You can get a clear view of how your AC works by examining the purpose of each key component.

1. Thermostat

The thermostat is the central brain of your AC. It tells the air conditioner when to run the cooling system and the fan. Your thermostat regulates airflow and cooling, using a centrally located temperature sensor to identify when the house has reached your desired temperature and when to start cooling again.

An efficient thermostat can help you save energy, and a programmable or smart thermostat can effectively optimize cooling cycles to match your household patterns and needs.

2. Refrigerant

The refrigerant is a unique fluid that expands and compresses in a way that can move heat from one place to another. It flows through the coils of your AC system in a continual cycle. When it expands into a gas, it can absorb heat, creating cold by removing heat from the inside of the AC unit. When compressed into a liquid, it releases that heat outdoors and starts the cycle over again.

Common refrigerants include R22 and R-401A (chemical designations). R22 is considered harmful and is being phased out, but some older units still use it.

3. Evaporator Coil

The evaporator coil channels refrigerant inside your house. When the refrigerant evaporates, it absorbs heat and creates a colder space. Warm air passes over the evaporator coil, which pulls out the heat making the air cold. That cold air is then cycled through your house while the warmer refrigerant is carried outdoors to the compressor and condenser coil.

4. Condenser Coil

The condenser coil is the other half of the equation. Your refrigerant fluid absorbs heat and travels outside to the compressor. It releases heat and transforms into a liquid when compressed inside the condenser oil. A fan inside the condenser helps to expel the heat while the refrigerant returns to a liquid state, ready to start the process again.

5. Compressor

The compressor is the big noisy box that sits outside, where heat can safely be released. The compressor is the system that forcibly compresses or condenses the refrigerant and contains the condenser coil. It applies pressure through electricity to compress the refrigerant while fans remove heat from the fluid lines so the refrigerant can become liquid again.

6. Expansion Valve

The expansion valve controls just how much liquid refrigerant is allowed to flow into the evaporator coil. High-pressure refrigerant is passed into the expansion valve. The refrigerant inside the valve expands and then cools to absorb more heat inside the house.

7. Air Handler/Blower

The blower fan, also known as the air handler, is how air is pushed from the AC unit into the rest of your home. The blower fan is also responsible for air intake, drawing new warm air to pass over the coils.

In a single zone AC like a window unit or one panel in a mini-split, the blower emits air from a single vent. For homes with central air, the blower provides air pressure so cool air can reach down the ductwork to every vent in each room of the house.

Central air blowers maintain consistent and even air distribution in the building.

8. Ductwork and Vents

The final component is the ductwork, capped by vents, for homes with central air. Ducts are sealed channels for cooled (or heated) air that travel throughout your house behind the walls and ceilings. They connect the AC unit to every room in the house, where cold air emits from the vents. Clean and seal the ducts to provide the best cooling efficiency and prevent energy loss.

Your AC

Knowing how the components of an air conditioning unit work together can help you diagnose problems when they happen. Is your thermostat reading the wrong temperature? Are your ducts blowing dust despite a fresh filter? Do you suspect that your refrigerant levels are low? Knowledge is power, and being informed can help you communicate your troubles more effectively with HVAC professionals when service is needed.

For professional AC, heating, and ductwork services, call Aztil.

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What Our Clients Think Of Us


Michael K. came out and did a wonderful job. There was condensation on my air filter and I was concerned about a leak. He was very thorough and made sure all avenues were checked. He also answered my questions and showed me parts on my AC. Great service!
Niko was great.
Niko was very patient and professional. Looking forward to cleaning this system.
He was great!
Niko came out promptly on a Saturday and fixed my problem easily. Great customer service
Response from the owner:Bernice Demanche, I'm glad to hear that Dana provided prompt service and fixed the issue easily. Excellent customer service can really make a difference in situations like these.
Niko was great- very informative
Niko very nice and did a good job explaining.
Niko, great service! Thank you!
Niko was personable and knowledgeable
Antonio was great and he was personable and I really do like him the next time that I have a visit from you guys it will be from him and I almost decided not to use you guys no more because of the other two gentlemen that came they were young boys, and they did not do things properly, but Antonio was very very good and I really liked himHe was very professional so thank you very much for letting Antonio come and giving yourself a second chance have a blessed day.
Nicholas (I think that’s his name) was very thorough and knowledgeable. I’m going to take his recommendation for a UV light. Please send him back to install when I order it. He furthers my trust in Aztil.
Response from the owner:Thank you for your review, Al Levy. We're so glad you had a positive experience with our appliance repair services!
Very happy with the service provided by Niko
Technician Lazaro Powery arrived much sooner than I expected. He looked professional, and his behavior matched his appearance. I really enjoyed our brief personal chat. I always ask people I deal with if their company treats its employees well, as it matters to me. I was happy to hear that he enjoys his employment with Aztil.

His professionalism and attitude well matched his positive comments. I'm not surprised as I find Aztil to be excellent people to deal with in all requests and transactions. Lazaro sets a good example for Aztil. Thanks for sending him. When he asked, I signed another one-year service contract
I had 3 terrific technicians Paul Gross who found the problem fixed it but also found a leak so I had 2 technicians Jordan and Hero come and do the duct work I was so impressed by all 3 of them their knowledge professional and the enjoyment in doing the work for their clients I give all 3 of 10 gold stars😀
AZTIL is a real COOL company and Jackie my rep @Aztil responds ASAP when I get HOT on the phone. Seriously Jackie’s the nicest person. I don’t want to leave anyone out but Juan the technician goes above and beyond trying to solve my HVAC problems.
Alex was very thorough and knowledgeable.
Tino was professional and friendly. Thank you for a great service over the years.
I have used aztill air conditioning service for over 15 years. They have always been prompt and have always done a great job. I recently would like to praise Dana who came to my home today and his boss Jack for the great price. My wife and I feel blessed to have found them. They have been reasonable in their prices and the technician are right on point. Thank you Aztill Air. 😁😃
This was my first experience with Aztil as a new homeowner. I purchased a service agreement which I thought was reasonably priced. My first scheduled maintenance was this past week by Michael King .He was extremely professional, knowledgeable and very kind in explaining everything I needed to know. He made a great suggestion in which I followed through with. He’s an asset to this very professional company. Thank you Aztil and Jonathan for a job well done!
Mike came by for an A/C maintenance check up. He came on time and was very friendly and professional.
Response from the owner:Hi Larry, thank you for taking the time to leave us such a positive review about Fabio. We are delighted to hear that he was on time and provided excellent service. We appreciate your feedback and are glad that you had a good experience. Thanks again!
Excellent service very knowledgeable Niko send him hereafter
Tino was exceptional in sevicing both of my AC its. I renewed my contract with Aztil and I look forward in having Tino service me again Thanks for great service
I had to have my air conditioning HVAC system replaced. I bought RHEEMS from them nine years ago or just shy of nine years ago and I had to have the whole thing replaced. It had a leak. The pressure was down 3 pounds and to pay $475 only because I had a contract with them otherwise it would’ve been 675 to check for the leak.. I decided to replace it cause I knew it was around the corner anyhow. They installed it the next day I couldn’t have been more pleased. It was effortless. It took them a while because we had some rain on and off and they couldn’t be on the roof, but they came at 9:30 and they left at 3 o’clock. I thought they did very well. They left my house clean as a button just exactly the way they found it. They were very polite and did everything that they were supposed to do in a very neat and tidy and timely manner.
Jorge and David were the installers today. They were timely, professional, mannerly, exceptionally clean and efficient. And Sabrina in their office went beyond in responding as the cost of new units today is sticker shock!
Nico is absolutely amazing! Very informative and an excellent technician! This is the second time we’ve had him and he’s great
Response from the owner:Hi Kathy, Thank you so much for your wonderful review! We're glad to hear that you had an excellent experience with our service. We pride ourselves on our knowledgeable staff, and it's great to know that Ramon was able to provide you with such great service. We appreciate your feedback and hope to see you again soon!
After 40 hours without A/C in August we were saved by Rafael. He was polite, professional and courteous. He is an asset to the company. On another note, the scheduling system used for after hours is quite poor and needs to be looked into. Thank goodness Jackie called us and attempted to remedy the situation.
Naraldo Bunsie did an excellent job installing my new Trane A/C! Thanks !
Michael was very knowledgeable and efficient in providing service for us today. We’d love for him to come again
Your service techs and general service has improved since the corporate take over. Raphael Curci was efficient and kept us u[p to date on the progress of the installation. The person I'd like to call out as exemplary was Nico who guided us through the process and went out of his way to help us through this time. Ultimately the air handler was faulty and it took several visits to repair it. Meanwhile the handler leaked water all over the garage ceiling ruining it and causing damage to my model trains beneath. In addition the last tech broke my cable power supply which he had no business touching. I had to call Xfinity to come as an emergency for which they charged me $150.00. I will also be sending Aztil a bill for the repair of my ceiling and any damage done to my model trains.
Dana just finished a service call. He was very professional and explained to me what he was doing and gave me tips for the future. I have been an Aztil customer for many years and people like Dana keep me coming back.
Response from the owner:Hi Don, thank you for your kind words! We're so glad to hear that Angel did an excellent job and that you were pleased with the outcome. Thank you for being a valued customer.
Michael was efficient and thorough. I am very pleased with this service.
Response from the owner:Thank you
Juan was fantastic!
Michael was great, he called in advance arrived on time, very professional and knowledgeable, and got the job done in a timely manner, highly recommend.
Michael provided excellent service on unclogging our drain line and explaining what options we have to prevent it getting clogged in the future.
Naraldo was was a competent and efficient skilled worker..
Doesn't talk much but gets the job done quickly.

Replaced and rewired our new water heater in a very short time.

Left everything clean and Sparkling..

Would have him return anytime for the next project that might pop-up.
Response from the owner:Hi Erlene, thank you for your kind words! We're so glad to hear that Rafael did an excellent job and that you were pleased with the outcome. Thank you for being a valued customer.
Dana Dussault, the technician that came to fix my AC and installed a new compressor was so efficient and courteous and is an asset to Aztil. I was very happy with the work.
Nico and Adrian were great. Cleaned my ac and found an oil leak. Very personable.
Response from the owner:Hi Ilene, thank you for your kind words! We're so glad to hear that Niko and Adrian did an excellent job and that you were pleased with the outcome. Thank you for being a valued customer.
Rico was friendly and very competent & efficient
Response from the owner:Hi Shanti, thank you for your kind words about Ricardo and Aztil. We are so glad to hear that you had a great experience with us. We will make sure to pass along your positive feedback to Ricardo. Thank you for choosing Aztil!
Dana came on a Saturday in the pouring rain. Totally professional and knew what was wrong right away. Great job guys!
Dana was efficient and effective and answered all my questions. Top notch
I had a new central AC installed by Aztil today. Both of the techs, Jorge and David, were professional and friendly. I used Aztil because I have used them for service for over 10 years and have been very satisfied. I can recommend them for service and installations.
Tino was great. Answered all our questions and took his time to explain everything
They came quickly and Lazaro was very professional.

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