How Does an Air Conditioning Compressor Work?
So how does your Air Conditioner Compressor Work?
Have you ever stopped and considered how your air conditioner system works and what keeps you cool here in Savannah, Georgia? An air conditioner works like a refrigerator by removing heat from inside your home and sends the heat outside. Only in this case, your home is the refrigerator. It also recirculates the newly cooled air throughout your home.
This transfer of heating and cooling happens when your compressor (a type of pump) moves the refrigerant or freon from the indoor portion of your air conditioning system to the outdoor condenser unit. The process of movement between heating and cooling, the indoor and outdoor portion of your house, happens because of the compressor.
Have you ever seen the large box that sits outside your home? A lot of people call this your AC Compressor. That is actually the condenser unit. Your compressor or pump is housed within the condensing unit and is a key part of your HVAC systems. The indoor portion of your air conditioner is typically in the attic, and it’s called the air handler or furnace. Sometimes your air handler is in a basement, or it could be located in a closet.
Your home’s central heating and air conditioning systems are made up of an indoor coil or an evaporator and a condenser. The latter is the outdoor unit, and then within the condensing unit is the pump.
The AC compressor serves as the go-between for the evaporator coil, or the coil that sits on top of your furnace, and the condensing coil, which is inside of the large box outside of your home. Your compressor works to pump refrigerant from the condenser outside of your home to the indoor coil.
Understanding Heat Transfer
The compressor is used to raise the temperature and pressure of the vapor refrigerant or gas, leaving the condensing coil through the discharge line. The compressor increases the pressure of the refrigerant so that it reaches a pressure difference. A high-pressure difference is needed for the refrigerant to flow correctly. The pump is raising the pressures as well as increasing the heat.
The heat transfer direction is from this higher temperature, high-pressure substance to a lower temperature, low-pressure substance, the lower temperature being the evaporator coil and the hotter temperature substance being the condenser.
So your refrigerant and oils will naturally migrate to the warmer portion of the system. Once your pump compresses the refrigerant vapor, it travels through the condenser coil and condenses the vapor refrigerant down into a liquid refrigerant. This high-pressure liquid refrigerant then travels through the suction line sets into the air handler’s indoor coil.
This is where it absorbs the heat from inside your house, and the refrigerant takes that heat back outside of your home. The indoor coil absorbs the heat from inside your home versus pumping cold air into your home from outside.
The freon’s heat is critical because the high-temperature refrigerant is so hot that the outside air will be cooler than the compressed refrigerant. This process is known as the refrigeration cycle.
Even with our summer temperatures getting up over 110 degrees, the gas pressures from the compressor are high enough to cause the temperature of the freon to be so high that pulling the hot 110-degree air across the coil is still going to cool the refrigerant down enough to cause it to condense into a liquid. That heat transfer between that 110-degree air and maybe 150-degree air is called condensing.
The heat that was transferred initially from inside the home’s evaporator coil is now coming to the outside module. It’s being pulled out of the refrigerant within the condenser coils by the fan that blows the hot air out of the top of the condenser.
Most everyone in Savannah, Georgia, has what is known as a vapor compressor. These are compressors that are cooled off by a fan pulling air across your coils. Some compressors are cooled by water coils. These are called water source heat pumps.
One thing to note is that a compressor does not compress the liquid. If you ever get liquid refrigerant back to your pump due to a dirty evaporator coil or dirty air filter, then it will cause significant damage to the internals of the pump. A compressor is a vapor pump, and these compressors will seize up if too much liquid arrives at the inlet of the compressor.
Compressor and Air Conditioner Maintenance
First and foremost, always follow the manufacturer’s guidelines when opening a system for cleaning or servicing. Also, be sure that you are a licensed and well-trained HVAC technician. Due to the dangers surrounding water and electricity, a well-trained service expert is the only person we would recommend performing any sort of tune-ups on your air conditioner’s refrigeration system.
During an air conditioning maintenance visit. Our service experts will pull apart your outside assembly, exposing your compressor. This is when we will clean all of the debris from the pump area, wash the coils thoroughly, and inspect your electrical components for any potential damage.
At this time, our service expert will test the wiring of the internals of your pump to ensure that nothing has shorted or has begun to short out and cause expensive damage.
Dirty Air Filter Damage
As mentioned before, if your filter is not being changed correctly or if your indoor coil is filthy, your system could potentially have liquid refrigerant getting back to the compressor. This constant compression of liquid is shortening the lifespan of this pump. This is why you must change your air filter every month. If your indoor coil is dirty, it is in your system’s best interest and your equipment’s longevity that we pull the indoor coil from the air handler and clean it properly with chemicals.
Low Refrigerant Damage
Just as important as keeping a clean air filter, ensure the system is running with the optimum amount of refrigerant. Operating your AC systems with low refrigerant levels will put a strain on the pump causing premature failure.
One of the most common occurrences you notice if your system is low on refrigerant is that the system will continuously freeze up. Air conditioners are a sealed system, and they do not require freon to be added to them every year.
If you have to add refrigerant to your a/c system every year, you have a refrigerant leak. It is essential that we repair the freon leak as soon as possible to prevent significant damage.
Air Conditioner Compressor Maintenance Q&A
What happens if your compressor fails? Below are a few options that you have.
Replace just the compressor.
While this makes sense if the system’s under warranty if this component is not under warranty anymore, this will be a costly repair! This repair can often be almost as expensive as replacing the whole outdoor module or the condenser.
Replacing the condensing unit
The condensing unit is the entire cabinet on the outdoor portion of your air conditioning. This is the part that you actually see most often. Some people have no idea there is actually an indoor portion to their air conditioners. This will be less expensive than replacing your entire system, but the problem lies in the fact that you will now have mismatched equipment with very little manufacturer’s warranty.
The other issue you now have is a powerful compressor and outdoor module matched to an old indoor coil. This can potentially cause massive leaks in your refrigerant circuit.
Replace the air conditioning circuit only
This basically means that you will replace the outdoor unit, the entire condensing unit, and the indoor evaporator coil if you have a furnace. When you do this, you won’t receive a partial warranty. You won’t have to worry quite as much about mismatched equipment.
The primary concern you will now be facing is that your indoor blower motor. Along with all of the dirt and debris accumulated over the years are still going to be there. You will not have a warranty on all of those components that were not replaced.
Replace the entire heating and a/c system
This includes the air conditioning unit, the indoor air handler, or the furnace. If you have a gas furnace, it includes the indoor coil. This will also include a full cleaning of your ductwork system. This is to ensure you have no issues with ducts leaking air from any of the joints. The replacement of the entire system will be the best option when it comes to comfort in your home.
Hopefully, we have helped you understand how an air conditioner compressor works. If you have any questions, if you’re still not clear on the difference between your compressor, your condenser, and your coils, do not hesitate to reach out to us at Service Emperor.
We are more than happy to send one of our experts to help you diagnose your air conditioner compressor. We are open 24/7 so if you need emergency service we are there for you.
This article is written by Tersh Blissett. CEO of Service Emperor and part-time HVAC Podcast Guru
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