In theory, a modern split system air conditioner should never need a recharge, unless it breaks. It’s supposed to be a closed system no different from your refrigerator. Most people never hear of a standard off-the-shelf refrigerator needing a recharge. Why is that? Well, let’s talk about your fridge for a moment to help me illustrate some points about your air conditioner. Hopefully, this will make sense to you in a couple of minutes.
Refrigerators Are Air Conditioners Too
Fridges are charged and tested in an ideal super clean, pristine, manufacturing environment. We’re talking surgically clean with masks and white suits and zero dust. During the manufacture of modern refrigerators, all moisture and other contaminants get removed, and the system sealed. It’s mostly a perfect situation. Most residential refrigerators have no service ports, and they are genuinely “closed” gas systems. Refrigerator units then have just the right amount of refrigerant gas circulated by a small compressor as it passed between the inside coil (to absorb heat within the fridge) and the outside heat exchange coil (to reject heat usually in the rear of the refrigerator). All good quality using simple designs means that basic refrigerators may operate trouble free for 20–30years or more. I say “simple” because most modern refrigerator service problems these days have nothing to do with the actual refrigeration system itself, i.e., the compressor, pipes, and the coils, etc. That “system” is quite sound and reliable. It’s the controls and accessories or “other systems” that tend to break in modern refrigerators. Ice makers, water dispensers, water filters reminders, clocks, cameras, wifi, etc. That’s the stuff that breaks most of the time. But the actual refrigeration gas system part rarely fails or requires service. Ok, so what does any of this have to do with a home air conditioner? Well, more than you might think.
Why Does My Air Conditioner Need Recharge?
If you understand that refrigerators and air conditioners are very similar in that they are closed systems, then why does my home air conditioner so often fail and need a recharge of refrigerant gas before my refrigerator? Good question!
It has to do with several factors, including the operating environment, the initial setup, improper maintenance, component failure, and incorrect service.
In no particular order, let’s talk about each of these factors:
When you think about it, your refrigerator has it pretty easy compared with your home air conditioner. The areas that each of them is responsible for cooling are drastically different. The air “conditioned” by each system – Fridge or Residence – differs dramatically in that the fridge has only to worry about a narrow band of temperature, whereas the home unit must deal with a much broader temperature range conditions between the outdoors and inside a home. The whole refrigerator system gets to sit in a friendly comfortable (for humans and pets) clean environment, but the home unit is separated or split between an indoor unit and an outside unit. Frequently, each component unit is sitting in a relatively hostile environment, such as a sweltering dusty attic, or outdoors in very undesirable hot or cold areas and dealing with insects, leaves, dust, and debris. This splitting of the home air conditioning system is, of course, necessary since we need to remove heat from inside the home. And we are dealing with a lot of air that needs conditioning. So the air conditioner needs big motors and compressors to drive big blowers and fans. These large devices generate heat and wear on moving parts. Dirt, moisture, extreme heat, extreme cold, insects, debris all take its toll. Depending on the environment, system failures and leakage may come more frequently. Seals and gaskets dry out and begin to leak. The freeze and heat cycle causes stress on bearings and wiring connections. Moisture and acid in the rain also accelerate oxidation in pipe connections and seals.
Unlike the refrigerator, assembled in a pristine ideal environment free of contaminants, the typical residential split system is the opposite. The home air conditioning system gets assembled in place by installer technicians usually wearing jeans, gloves, and hats. The techs unbox and place the major indoor and outdoor components, and they connect them using special copper pipe (line-set) that usually needs to be completed using heat or special fittings. Once the tubes are connected, the tech must pressure test the lines and remove ALL moisture from the system. A lot of things can go wrong during this whole stage of installing or replacing an air conditioner. Moisture and contamination in the system is the enemy. It can slowly (or rapidly) damage an air conditioning system from the inside out. Much depends on the quality of the installation and the degree of moisture removal and cleanliness practiced. The lower the quality of the installation process, the sooner that leaks may begin forming from the inside out due to sensitive oil contamination or acid formation.
Unlike most refrigerators, most home air conditioning systems require a certain amount of routine maintenance. The air movement system needs to have the air filter(s) replaced when they are dirty to keep dust from building up too quickly inside the unit and restricting air flow and causing the blower motor to work excessively hard. The outdoor coil needs to remain clear of debris and dirt, and the exhaust fan needs to be free of trash too. Some maintenance may need to be performed by a professional, such as checking the condensate drain system as well as vent and duct connections remain sealed and tight. Check on the line set insulation and look for any moisture. The technician will be able to assess the complete health of your system by measuring temperatures of the air and refrigerant lines as well as the power used by the electrical motors and compressor during operation. Visually the tech will check for any signs of refrigerant oil or moisture where it doesn’t belong. You’ll note that it is NOT necessary to break open the refrigeration lines to check pressures to know if a system is operating correctly. It is NOT required to open the system, and pressure gauges get connected only when other indicators, above, suggest a refrigerant system related problem. With that said, all too often, the technician will grab the gauges and connect anyway, and that act alone begins to remove refrigerant from the system and decreasing efficiency at least slightly. If this is an annual maintenance check-up, well, after a few years, there will be a need to top off or recharge to return the system to proper efficiency.
An ideally implemented air conditioner system is one that is moisture free, and that is a “closed” system having precisely the correct amount of refrigerant gas for its type and size. Sometimes improperly trained air conditioning technicians are too quick to connect gauges to an otherwise healthy and pristine system, thereby opening the “closed” system. In at least a small way, they have caused some refrigerant loss. It’s unavoidable. Their instrument hoses hold a small amount of air that must be purged to get proper readings. Then when they disconnect the gauges, there is at least a small amount of gas loss too. Over the years it adds up. Also, consider that the service port valves themselves can become worn from time and begin to leak ever so slowly too. And, at some point, a tech will probably need to “top you off” and here is where even more care must be taken to avoid accidentally introducing air/moisture into the air conditioning system. Over time a slightly lower or higher than the correct amount of refrigerant gas in an AC system lowers efficiency.
At some point, typically between 12 and 20 years, you will likely be told that you have a major component failure. If you’re lucky, it will happen under warranty, and the indoor or outdoor component gets replaced as a unit by a technician. If it’s electrical, such as a motor, capacitor, relay, etc., it’s easily found and fixed. Electrical type AC failures do not usually impact the gas part of the system. If however, the problem requires a replacing the indoor or outdoor air conditioning unit, that’s much more drastic. Once the replacement unit is in place, the whole installation process must happen. Reconnect the copper pipes, pressure test, and evacuate the system to remove all the moisture and recharge.
So We Recharge
This brief article is not an exhaustive list of reasons for why one might need to have their Air Conditioner recharged, but I am hoping that it does shed a little light on how it all works and why we sometimes can be our own worst enemy. With more training and better tools, and more consumer education about air conditioners, things will continue to get better and better.
Hats Off To Great Technicians
By writing this response, I certainly do not mean to suggest that all HVAC technicians are hacks, dishonest, and anything less than well-meaning. Nothing could be further from the truth. However, like any vocation, some technicians are better informed and trained than others. It’s up to you to ask questions and educate yourself in order to assess someone who is going to work on your equipment. Neighbor reviews are fine and good, but what does your neighbor know about HVAC? Seriously, this stuff is complicated. It’s not washing dishes. Do some legwork, learn a little bit about best practices and why they matter. Learn about the companies in your area and their credentials and training, etc. Once you’ve got a good one, hold on and accept no other without another round of research. You’ll be glad you did. Trust but verify.
Hope this helps!