What Is an Inverter Air Conditioner?
Operating quietly and reducing energy consumption by up to 44%, inverter air conditioners are easy to sell.
An inverter air conditioner owes its energy efficiency to advanced inverter technology that allows the compressor to adjust its speed based on your cooling needs.
That said, choosing an inverter AC isn’t always a no-brainer. There are still factors you may want to consider when selecting this split system air con.
In this post, you’ll learn more about how the inverter technology in AC systems works and, if you choose to go the inverter way, how to select the right air conditioning install for your space.
Table of Contents
What Is an Inverter Air Conditioner and How Does It Work?
An inverter air conditioner is a type of AC that maintains the target temperature by automatically adjusting the amount of heat it removes from a room.
Two parts differentiate it from non-inverter models: a variable frequency drive (VFD) and a variable-speed compressor motor.
The VFD sits between the wall socket and the compressor. It contains a rectifier, capacitors/DC bus, and an inverter circuit.
Here’s how the VFD in an inverter air conditioner works with the compressor to maintain the target temperature.
Inside the VFD:
- The rectifier converts incoming alternating current (regular electricity coming into your home from the grid through the main outlet) into direct current (DC). However, this DC is pulsating or unstable.
- The capacitors smooth the pulsating DC to produce a stable DC supply.
- Finally, the inverter circuit (the chief component of the VFD) transforms that DC back into alternating current, but at whatever frequency the AC board demands.
For example, if you’ve just switched on your inverter AC and set the target temperature to 22°C while your room’s temperature is 30°C, the board may ask the inverter circuit for a high-output frequency, say 90Hz or more, to bring the room’s temperature down quickly.
The inverter circuit responds by producing alternating current at the requested frequency. The compressor motor spins fast, the refrigerant cycles aggressively, and the unit removes heat from the room.
As the room temperature drops and gets closer to 22°C, the control board steadily lowers its demand. The inverter circuit might shift to 60Hz, then 40Hz, then 25Hz, slowing the compressor down in step with the shrinking gap between the actual and target temperatures.
Once the room is at 22°C, the AC board tells the inverter circuit to lower its output frequency significantly, just enough to offset the heat creeping back in from outside. It keeps running quietly at this reduced speed instead of switching off entirely. If you open a door or the outdoor temperature climbs and the room warms up again, the control board detects the change and pushes the frequency back up.
Since the compressor motor operates at a variable speed, it’s capable of slowing down or speeding up according to the demands of the inverter circuit.
Now let's compare this process to how a non-inverter unit operates.
First, a non-inverter unit has no inverter, meaning that there’s no built-in module for performing an alternating-current-to-DC-and-back-to-alternating-current conversion loop.
Consequently, it feeds incoming alternating current directly to the compressor motor. The compressor motor typically runs at a fixed speed rather than a variable speed, so it’s either fully on or fully off at any given moment.
When the room is warmer than the target temperature, the compressor immediately runs at full speed and cools at maximum capacity.
Once the room reaches the target temperature, the compressor stops running entirely. The fan may keep blowing, but no active cooling is happening.
The room warms up gradually until it drifts a degree or two above the set temperature, then the compressor starts running again till the room reaches the target temperature, after which it stops again.
This start-stop pattern continues for as long as the air conditioner is on. That’s why non-inverter air-cons make that “clunk” sound occasionally; it’s the announcement of the compressor’s starts and stops.
Inverter Air Conditioner vs Non-Inverter: Core Differences
The biggest difference between both conditioner types is the compressor.
Non-inverter systems use fixed-speed compressors. Fixed compressors either run at maximum capacity or switch off altogether.
Inverter air conditioning systems, on the other hand, employ variable-speed compressor technology that adjusts motor speed in real-time based on cooling demand.
In a 2020 study published in Energy Transitions, researchers found that inverter air conditioners consumed 44% less electricity than non-inverter air conditioners. They also calculated that inverter usage resulted in 49% less greenhouse gas emissions.
This efficiency stems from avoiding the constant start-stop cycle, which creates energy spikes each time the compressor restarts at full capacity.
If a non-inverter unit is running, you’ll notice temperature fluctuations as it cycles on and off. Inverter technology in AC units helps them maintain consistent temperature and fine-tune compressor speed moment by moment. This eliminates the peaks and valleys typical of fixed-speed systems.
Non-inverter models generate more noise, especially when the compressor kicks in. Inverter systems operate more quietly through continuous low-speed operation rather than repeated high-power starts.
The start-stop operation of non-inverter systems causes more mechanical stress and increases breakdown risk. Inverter units experience less wear despite containing more advanced components.
What Are the Disadvantages of Inverter AC?
Despite their efficiency, inverter air conditioners come with drawbacks that impact purchasing decisions.
Inverter models cost 30% to 50% more than non-inverter units. This price accounts for the advanced compressor technology and control systems, but it also raises the barrier to purchasing inverter air conditioners.
Owners are usually shocked at how high repair expenses can be. Besides standard mechanical components present in non-inverter units, inverter air conditioners contain electronic parts like a VFD, multiple sensors, and sophisticated printed circuit boards (PCBs). Replacing just one PCB can cost up to 50% the price of a brand new inverter air conditioner.
Inverter air conditioning relies on electronic components that are prone to damage if electricity supply is irregular.
Many inverter models are designed to handle wide voltage ranges, typically between 145V and 290V, with a safe threshold often around 140V. When voltage drops below this threshold, the AC shuts down automatically to protect its electronic components from damage.
Staying in a suburb with persistent voltage instability? You may need an external stabiliser. While an inverter air conditioner can protect itself if necessary, relying on built-in protective features can be risky.
Installing and Maintaining Inverter Air Conditioners
Installation
Professional installation is non-negotiable for inverter air conditioning systems. Qualified F-Gas engineers must handle installations per EC/517/2014 regulations in the European Union. Some manufacturers void warranties if unlicensed tradesmen perform the work.
At BG Electrical, we’re fully licensed and qualified to install, wire, and service air conditioning systems in Queensland.
While the contractors you hire will be responsible for executing installation decisions, knowing these best practices will help you flag poor workmanship:
- Location selection directly affects unit performance. Indoor units should be mounted on solid walls at least 2.3 metres above ground, positioned on a level base, and away from heat sources.
- Outdoor units need areas with good ventilation and solid, level bases that prevent vibrations. The outdoor compressor should sit clear of obstacles that block airflow.
- Refrigerant lines must be routed without kinks or stress points and properly insulated to prevent condensation and energy loss.
- Wiring must not touch the compressor, refrigerant tubing, and any moving fan parts to avoid heat damage or physical wear.
Maintenance
You can clean external vents and rinse filters yourself, but full servicing requires licensed technicians. Never attempt electrical panel work or refrigerant handling without qualifications.
Filters should be cleaned every two to four weeks during periods of regular use and replaced only when damaged or when the manufacturer recommends. Ensure you get your inverter air conditioner professionally serviced at least once a year. If running a system in a dusty environment, you may want to consider getting it checked every six months.
Servicing typically covers:
- Cleaning the indoor and outdoor coils
- Clearing the condensate drain line
- Checking refrigerant pressure and topping it up if needed
- Inspecting electrical connections and capacitors
- Testing sensor accuracy, and
- Running the system through its cooling cycle to confirm performance.
The technician will also check the outdoor unit’s fan motor and blades, remove any debris that has built up around it, and inspect the compressor for signs of wear.
How to Choose an Inverter Air Conditioning System
Selecting the right inverter air conditioning system requires matching capacity to your specific circumstances rather than guessing based on floor area alone.
Room dimensions determine the kilowatt capacity you just need. Small spaces under 20m² require 2.0–2.5 kW units. Medium rooms between 20–40m² need 2.5–5.0 kW, and large areas from 40–60m² just need 5.0-7.0 kW systems.
Ceiling height affects these calculations. Rooms with 2.4m ceilings need 150 watts per square metre, and 3m ceilings require 175 watts per square metre. Insulation quality and window orientation alter requirements further. Get a professional load assessment done; it’s more reliable than any online calculator.
Climate zones affect cooling demands a lot. It’s advisable to go 10–20% higher than the maximum capacity for your room size if temperatures regularly average above 35°C.
Usage frequency matters just as much. Higher-capacity systems are more expensive upfront, but if used for long periods daily, lower electricity bills significantly. Buyers intending to run their inverter air conditioners occasionally may want to opt for lower-capacity systems.
What Is the Best Inverter Air Conditioner?
There isn’t a single best inverter air conditioner per se. What’s important is the specifications of the particular model you’re considering.
Check energy efficiency ratings, cooling and heating capacity, indoor noise levels, warranty lengths (particularly on the compressor), and price. A premium 2.5kW unit with a 7-star ZERL rating will be more energy-efficient than a budget 2.5kW unit with a 3-star ZERL rating from the same brand. For context, ZERL stands for “Zoned Energy Rating Label”, and it’s used to measure air conditioner energy efficiency in Australia.
At BG Electrical, we have over 15 years of experience installing inverter air conditioners from a wide range of brands. We can help you choose a model that matches your room size, climate, usage pattern, and budget, then install it to the standards that protect your warranty and keep the unit running efficiently for years.
Frequently Asked Questions
Inverter models outperform traditional systems in energy efficiency, temperature stability and noise reduction, but your usage patterns determine overall value. Non-inverter units are suited for occasional use in large rooms where upfront costs matter more than long-term savings.
Inverter air conditioning serves the same cooling and heating purposes as traditional systems but delivers these functions with improved energy efficiency. The technology excels in maintaining steady indoor temperatures for extended periods. This makes it ideal for households running air conditioning daily throughout warmer months.
Inverter systems outlast non-inverter models, with average lifespans around 10 years. Because their compressors operate continuously at variable speeds, they are under less mechanical stress compared to the constant start-stop cycles of fixed-speed compressors. This extends equipment durability.