Central Air Conditioner Parts
Air Conditioning: Condensor
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
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 Especially if you have an out of date, now obsolete R-22 system.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
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
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'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
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.