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Central Air Conditioner Parts

Updated on March 22, 2014
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Dan has been in the HVAC industry for 22 years with experience in aspects ranging from installation and service to sales and distribution.

Air Conditioning: Condensor

Though many refer to this as their air conditioner, truly it is only part of a split system. The condenser it the proper name of this unit because it condenses the refrigerant back into a liquid from a gas.
Though many refer to this as their air conditioner, truly it is only part of a split system. The condenser it the proper name of this unit because it condenses the refrigerant back into a liquid from a gas. | Source

The Condenser is the Main Working Component in an A/C System

An air conditioning system is rather simple really in the amount of parts it's made up of. In reality, the system is made up of 2 main components, the condenser and the coil. There are other things that are a necessary to connect and help the system function but they aren't dedicated solely to the A/C system. For example the thermostat and the furnace, or air handler, are not solely belonging to the air conditioning system.

With that said, the condenser is the only real mechanical part of the system. The evaporator coil is really just a box of fins and tubing with a drain attached to carry off the condensation it collects.

What I aim to do is explain only the parts of the condensing unit. This is the piece where the problems will likely occur and the more you know about what it's made up of, the less likely you are to be "taken" by a shady service technician. It's unfortunate but, they are out there.


Air Conditioning: Compressor

This is a top view of the compressor located in the center of the condensing unit. Other than cleaning your unit, you shouldn't really be in here but do note if you are, this may be very hot. Especially some of the copper lines attached to it.
This is a top view of the compressor located in the center of the condensing unit. Other than cleaning your unit, you shouldn't really be in here but do note if you are, this may be very hot. Especially some of the copper lines attached to it. | Source

The Compressor

The compressor is the head honcho in the air conditioning system. If it breaks down, forget fixing it yourself and carefully weigh the expense of replacing it verses getting a whole new system. Especially if you have an out of date, now obsolete R-22 system.

Today's compressors are what is called "hermetic", meaning sealed. There is no opening them up and putting them back together. They are also nearly all of the scroll type. This means that instead of a piston pushing up and down on the refrigerant, it is a rotating component that is doing the work. This is beneficial since the impact of a piston is not good for itself. Plus, the scroll type will be much quieter during operation.


Air Conditioning: Condenser Fan and Motor

Here the condenser lid is removed so that you can see the fan and motor. Notice the solid housing on the motor. Be sure your fan spins freely with your hand and if not, lubricate the shaft so that it does.
Here the condenser lid is removed so that you can see the fan and motor. Notice the solid housing on the motor. Be sure your fan spins freely with your hand and if not, lubricate the shaft so that it does. | Source

The Condenser Fan and Fan Motor

The condenser fan and motor are an essential part of the air conditioning system as well. This fan is used to pull air through the coils of the condenser to help cool the refrigerant and compressor as well as displace the heat that is coming off of those parts. This is why the fan is blowing warm air out of the unit. This is also why cut grass, leaves and "fuzzies" are pulled into the fins on the coils which must be kept clean for good airflow. With the air being drawn in by the fan comes all sorts of things that block air and keep our condenser from working as efficiently as it should.

These motors are sealed so that rain cannot get into the working parts of the motor. Be sure that if you have the motor replaced that the housing of the motor is solid and does not have "breather" ports on it. Some do not realize this difference and assume a blower motor can be used to replace a condenser motor. This mistake will surely cause problems if made.

NOTE: The condenser fan motor and compressor are the 2 parts that you want to be sure have a decent warranty when making an A/C system purchase. Most other parts will have only a year long warranty but are rather inexpensive to replace if needed later. Not so much for the fan motor and compressor.


Air Conditioning: Condenser Coil

When the condenser is stripped down, it's really just a bunch of coils and fins that are typically referred to as the condenser coils.
When the condenser is stripped down, it's really just a bunch of coils and fins that are typically referred to as the condenser coils. | Source

The Condenser Coils

The condenser coil is where the process of therefrigerant returning from a gas to a liquid begins. There is no mechanical function here. The coils either contain refrigerant or they don't. Of course if they don't, you have a problem on your hands.

Air conditioning is all about the relationship between temperature and pressure. These two things together are manipulated so that the refrigerant in the system will change back and forth from liquid to gas. This is a very nutshell explanation of how air conditioning works but that is another conversation all together.

The coil area of a condenser has a significant impact on how efficiently our air conditioner is. You may have noticed that lately, the air conditioners that people are having installed are much larger than those they replaced. This is largely related to the fact that energy regulations have commanded that the minimum SEER rating (efficiency rating) be increased over the last few years.


Air Conditioner: Capacitor

The capacitor is guilty of costing many homeowners a significant amount of money when it blows. It's also responsible for providing significant income to service providers. Buy one and keep it on hand.
The capacitor is guilty of costing many homeowners a significant amount of money when it blows. It's also responsible for providing significant income to service providers. Buy one and keep it on hand. | Source

The Capacitor

The capacitor's function is rather simple, to provide a boost of electricity to help start or run motors. It sort of works like a battery in the respect that it stores power. When the air conditioner is asked to operate, the capacitor discharges this stored energy, providing a boost to get the motor going.

These capacitors do blow and when they do, it's really quite simple to diagnose and replace. You may see an oily discharge, in some cases, dripping down the side of the capacitor or perhaps yours won't entirely "pop" and instead, just the top will be humped up. This top should be flat. Of course the first thing you'll notice is that your A/C isn't working and that the fan is not spinning.


Air Conditioner: Contactor

Contactors don't typically go bad. Many times they malfunction, it is because of carbon build up on the surface that is to make contact.
Contactors don't typically go bad. Many times they malfunction, it is because of carbon build up on the surface that is to make contact. | Source

The A/C Contactor

The contactor is a sort of power bridge. In the photo, you can see a button in the center of the component. This button serves as a drawbridge. When the thermostat tells the furnace that it wants cooling, the furnace then relays this message to the contactor via a 24V signal. When the 24V hits the contactor, it creates a magnetism that pulls in this button, thus closing the bridge and allowing power to cross through to the condenser fan and compressor.

Here is where you may sometimes see that your A/C fuses are blown. You may hear the unit humming and see that the contactor button is pulled in but nothing is happening. This is likely because the fuses protecting the unit are blown and though the button is pulled in, there is no power waiting to "cross the bridge".

NOTE: There is 220V passing across this drawbridge. It's certainly not the type of bridge you care to play around with if you prefer to keep control of your own functions.

Things That Make You Say, "Really?"


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Air conditioning systems are rather simple. It's the science that is difficult to understand.

That's it really. Some more modern, advanced air conditioning condensers do have an electronic control board but typically, what I've shown you is all you have in your condensing unit.

Now as I mentioned, the condenser is the main unit but it cannot operate without help from it's friends. There must be an indoor fan to move the air, a thermostat to tell the unit when to turn off and on, and an evaporator coil to help manipulate the refrigerant and absorb the heat from within your home.

I hope you feel that you know a bit more about your A/C system and what it is made up of. Just remember, when it comes to your A/C, always take care when maintaining the system. Turn off the power, be careful not to bend any of the fins or copper tubing and never open the refrigerant valves or tubing to the atmosphere. Not only is this harmful to the environment but it can cause severe burns and is against the law with very heavy repercussions.

Questions & Answers

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      • Cre8tor profile image
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        Dan Robbins 4 months ago from Ohio

        Ellen - If a test has been run that the capacitance is low then it's a matter of time and I'd replace it before it becomes an inconvenient problem. Thank you for reading.

      • profile image

        Ellen 4 months ago

        What happens when the capacitor is bad but not blow yet?

      • Cre8tor profile image
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        Dan Robbins 2 years ago from Ohio

        Hi Tom, Contact your local Tempstar dealer and give them the model and serial number and they can special order that in for you. It's not likely something anyone will stock so you'll likely be looking at the cost plus shipping and tax.

      • profile image

        tom 2 years ago

        I need the "lid" that the motor is mounted to...have a tempstar ...but can't seem to find the lid. Lookds exactly like the one at the top of the page.... can anyeone help...????

      • tipstoretireearly profile image

        tipstoretireearly 4 years ago from New York

        Very helpful. A/C units are really fairly simple once you break down their components the way you've done.

      • Cre8tor profile image
        Author

        Dan Robbins 5 years ago from Ohio

        @ SOMEONEWHOKNOWS - Geo-Thermal is the wave of the future......once the average individual can afford it. You are absolutely right though. The fact is, and I know from experience, people can hardly afford energy costs therefore breakdowns force them to go without. Times are hard and people have turned down my services in the dead of winter and heat of summer because they couldn't afford it no matter how low the price....a big part of why I write these hubs.

      • stars439 profile image

        stars439 5 years ago from Louisiana, The Magnolia and Pelican State.

        Great hub. Very informatuve. GBY.

      • profile image

        SOMEONEWHOKNOWS 5 years ago

        If electricity costs Increase we may have to resort to less exspensive methods of keeping our cool.Maybe heat transfer to and from pools of water. This would be insulated pools of water

      • American_Choices profile image

        American_Choices 5 years ago from USA

        Amazing - all the things I never knew. This is critical information for all homeowners. Thank you! Voted up and rated awesome - keep up the fantastic work.

      • Cre8tor profile image
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        Dan Robbins 5 years ago from Ohio

        @oscarlites - I know it can be tough but many of my hubs explain that though this is the case, HVAC supply houses will often help you if you are prepared with the information they need to help you. This tells them you won't kill yourself working on the unit. That is parts that aren't proprietary or require an EPA license. This is largely out of their hands. Thanks for your comments.

      • Oscarlites profile image

        Oscar Jones 5 years ago from Alabama

        just got done having to replace the fan motor on the outside unit.. once i got the rigth motor it was easy.. sometimes you can't get the brand name part, or have to have a license. etc.

      • Night Magic profile image

        Night Magic 5 years ago from Canada

        Congrats on Hub of the Day. Good info. I didn't do very well on your quiz

      • Cre8tor profile image
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        Dan Robbins 5 years ago from Ohio

        Thanks everyone for your congrats and support. I really do appreciate it and hope that I've been able to provide you with something you'll be able to use. I would reply individually however my reply button is MIA so I hope this will do in it's place. Thank you again and thank you to HP for selecting this for HOTD.

      • melpor profile image

        Melvin Porter 5 years ago from New Jersey, USA

        Very good hub and congratulations on your hub being selected for "hub of the day".

      • Emma Harvey profile image

        Emma Harvey 5 years ago from Berkshire, UK

        Great hub and very well written. Congratulations on your Hub of the Day!

      • Happyboomernurse profile image

        Gail Sobotkin 5 years ago from South Carolina

        Excellent article. You have taken a topic that is intimidating to most homeowners and given simple, well illustrated information that explains the basic parts of the air conditioning system.

        Voted up across the board except for funny.

        Thanks for sharing this info.

      • JayeWisdom profile image

        Jaye Denman 5 years ago from Deep South, USA

        This is an excellent hub, Cre8tor....It's so nice of you to share this specialized information, and you did it so well--photos and all.

      • Billie Pagliolo profile image

        Billie Pagliolo 5 years ago from Laguna Hills, California

        Excellent!! Maybe you'd get a laugh from my essay "Air Conditioning the Path to Hell" Actually this year was the hundreth anniversary of the air-conditioner, right? - the greatest invention ever! BTW... I'm typing with a clear view of our rickety old air conditioner. UGH! Do you have suggestions block the view without interrupting the functioning. The side facing me borders the patio cement block and the other "3 sides" are in strip of garden space. The top is a wreck and view-able. We need a new one, but...

      • Daughter Of Maat profile image

        Melissa Flagg COA OSC 5 years ago from Rural Central Florida

        Hey Cre8tor, congrats on another HOTD!!! :D

      • ktrapp profile image

        Kristin Trapp 5 years ago from Illinois

        Stopping back by just to say congratulations on Hub of the Day. All of your HVAC hubs are incredibly useful for us often-baffled homeowners.

      • Marcy Goodfleisch profile image

        Marcy Goodfleisch 5 years ago from Planet Earth

        I just had to check this one out again! Such a helpful hub - congrats on being selected as HOTD! So deserved!

      • howlermunkey profile image

        Jeff Boettner 5 years ago from Tampa, FL

        Great Hub, bookmarking this one for future reference. Voted up and shared.

      • Cre8tor profile image
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        Dan Robbins 5 years ago from Ohio

        Thank you Juggler. (I like the handle)

      • GoForTheJuggler profile image

        Joshua Patrick 5 years ago from Texas

        Great, informative hub - congrats on Hub of the Day! Voted up across the board.

      • Cre8tor profile image
        Author

        Dan Robbins 5 years ago from Ohio

        Thanks Simone! Your inspiration is greatly appreciated!

      • Simone Smith profile image

        Simone Haruko Smith 5 years ago from San Francisco

        Whoah, how cool it is to actually know what's going on inside these things! I love this Hub, and the photos and your explanations are incredibly useful. You rock, Cre8tor!

      • Cre8tor profile image
        Author

        Dan Robbins 5 years ago from Ohio

        @ Marcy - I'm glad this was helpful. Knowing what these things are and do will help make people more comfortable with their services that are being performed. (That they're not being ripped off.)

      • Marcy Goodfleisch profile image

        Marcy Goodfleisch 5 years ago from Planet Earth

        Ah, yes - yet another piece of my home that's getting ready to crater! I'm so glad to see this glossary of terms. I'm lost when the repair crew comes out and rattles off the list of what's ailing. Thanks!

      • Daughter Of Maat profile image

        Melissa Flagg COA OSC 5 years ago from Rural Central Florida

        It is one of those weird tidbits that no one would really know unless chemistry was your thing. I just asked my hubby the question and he was like "well I think its combustible, but I don't know..." lol When I told him the answer he was like "So THAT's what that is...." lmao

      • Cre8tor profile image
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        Dan Robbins 5 years ago from Ohio

        Thank you so much DOM! Never a pest at all. I am glad that I can be of help. This is my motivation. Thanks for keeping the answer to yourself. I always thought this was an interesting tidbit and think some may be very surprised to know that this is really that! ;)

      • Daughter Of Maat profile image

        Melissa Flagg COA OSC 5 years ago from Rural Central Florida

        Wow, fantastic hub Cre8tor, now I can bookmark it instead of pestering you with questions lol.

        I actually knew the answer to the quiz, I actually surprised myself! (I won't reveal the answer so no one can cheat lol)

        Voted up awesome and shared!

      • Cre8tor profile image
        Author

        Dan Robbins 5 years ago from Ohio

        You're welcome. My goal is always to make these things easier for the average homeowner to understand. Knowledge is power.

      • ktrapp profile image

        Kristin Trapp 5 years ago from Illinois

        Thanks for demystifying how an air conditioner works. I wish I knew all of this in the past when I've had HVAC guys out to do repairs so I could better understand them.