Most drivers know, turning on the air conditioner will make the car use more fuel. But how much it costs, and how specific the number is, not everyone knows.
To answer the question “How much gas does AC use in a car?” follow this article!
In modern technology life, air conditioning has become one of the indispensable pieces of equipment in every vehicle.
And a problem that is always questioned and a concern by drivers is whether turning on the car air conditioner will cause too much fuel consumption, how to minimize fuel consumption when turning on the air conditioner on the car?
Introduction to Car AC and Heating Systems
To understand how air conditioning and heating in a car affect gas usage, it’s essential to know the basics of how these systems operate.
The car’s AC system functions by compressing refrigerant and passing it through an expansion valve, which causes it to cool down.
A fan then blows air over the cooled refrigerant through the evaporator, thus providing refreshing, chilled air within the vehicle’s cabin.
The compressor is spun by an AC or serpentine belt, driven by the crankshaft, but when it’s not in use, the compressor disconnects using a clutch on the pulley.
Heating in a vehicle, on the other hand, typically uses the heat generated from the car’s engine that would otherwise be wasted.
The coolant absorbs this heat, and as it circulates through the heater core, a fan blows the warm air produced into the cabin, providing the warmth you feel.
How Does the Car Air Conditioner Work?
A general overview of how a typical car air conditioner works can help you understand its negligible impact on fuel consumption.
The car’s AC uses energy from the engine to cool the cabin temperature. Here’s how it works:
- Compressor: The heart of the air conditioning system is the compressor. It compresses the refrigerant gas, raising its temperature. The compressor is the component that indirectly uses power generated from the vehicle’s fuel.
- Condenser: The hot refrigerant gas flows through the condenser (a series of coils), releasing heat. The cooled gas condenses into a cold liquid.
- Receiver-drier: Refrigerant passes through a reservoir that removes water from the line, which, if not removed, can create ice crystals and damage the AC system.
- Expansion valve: A valve restricts the refrigerant flow, causing it to expand and change from high-pressure to low-pressure refrigerant.
- Evaporator: The liquid refrigerant passes through the evaporator, absorbing heat from the cabin air and cooling it down.
- Blower fan: The blower fan circulates the cold air outside the evaporator into the cabin.
Does Car AC Use Gas?
Yes, the car air conditioner does use gas, but not directly, and not that much. The vehicle’s engine uses gas to power the alternator; the alternator provides energy for the compressor in the AC system.
Here’s how it impacts fuel economy:
- Engine load: When you turn on the air conditioner, the engine has to work harder to power the compressor. This additional load on the engine results in increased fuel consumption.
- Fuel efficiency: Some studies have shown that using the air conditioner can reduce fuel efficiency by up to 10%. However, the impact varies depending on factors like outside temperature, driving speed, and the car’s make and model.
- City vs. highway driving: The impact is more significant during city driving, where frequent stops and starts require the engine to work harder. On the highway, the impact is relatively lower.
How Much Gas Does AC Use?
According to the data we got from the Energy Star website when turning on the AC in your car, it will consume from 0,5 to 1 gallon of gas per hour. And of course, this number will increase when driving during the peak hour.
The results show that turning on the air conditioner will have the strongest effect on hybrid cars, the distance running in the city will decrease by up to 9.3% and down 2.8% when running on the highway.
And the average rate is up to 6.1%. For example, a 2015 Chevy Volt with a full tank can run for more than 600 miles, when the air conditioner is turned on and the car drives in the city area, the running distance is reduced by 56 miles, equivalent to a decrease of 9.3%.
Diesel vehicles are the second most affected vehicle by air conditioning, with a drop of about 6.3% in the city and 3.3% on the highway, an average of 4.6%.
Particularly, gasoline engines had the lowest impact, only decreasing by 5.1% in the city and 2.7% when running on the highway, respectively, 3.8%.
However, these results are for reference only because the actual consumption level depends on many other factors.
Causes of Car A/C To Burn More Gas Than Usual
Besides frequently cycling your A/C on and off, there are a few other things that can lead to higher fuel consumption for your A/C but not all of them are under your control.
However, don’t stress this too much, and using gas is part of driving your car. Everything from your car’s radio to your car’s headlights uses gas so don’t get too obsessed with your mpg!
#1. Malfunctions and Breakdowns.
Just like any machine, your car’s A/C system can break down. But unlike many other aspects of your vehicle, the A/C system doesn’t get as much routine care.
There aren’t regular maintenance filters and while there’s something called a receiver dryer that collects moisture it isn’t changed regularly unless there’s a problem.
Lack of refrigerant is a problem, not a maintenance thing. The A/C system is a sealed system and there shouldn’t be any leaks in it. Usually when there is a leak it just won’t work very well.
#2. Extreme Outside Temperatures.
Using your A/C on maximum during extremely hot days can place a higher load on the engine. The hotter it is outside, the harder your A/C works to cool down the inside of the car.
There’s not much you can do here but if you’re really worried about saving some cash and literally going the extra mile, consider driving in the morning or evenings when it’s cooler.
#3. Using the ‘Max’ Setting Continuously.
While it’s tempting to blast the A/C on the coldest setting, doing so constantly can put a continuous load on the engine, leading to increased fuel consumption.
It’s okay to max it out a bit, but keep it steady when you can and about 20% below the max setting.
Low AC vs. High AC: Which Settings are Best for Gas Mileage?
There are two air conditioner settings to consider in your vehicle: the temperature and the speed settings. Each of these settings affects your gas mileage in different ways. Let’s take a closer look:
- Temperature settings: Lower AC temperatures will require more gas than moderate temperature settings, so consider setting your car’s AC temperature as high as comfortably possible to save gas.
- Speed settings: Truthfully, once you turn your air conditioner on and set the temperature, it does not matter how high you run it. Your air conditioning compressor uses gas to run your system. However, the motor that controls how high or low your AC system runs is often powered by the alternator. In other words, running your air conditioning on full blast will use just as much gas as running it on its lowest settings.
As such, it is best to use the most moderate comfortable temperature setting on the highest speed for maximum comfort and savings.
What Affects Gas Mileage When The AC Is ON?
The impact that running your A/C has on fuel consumption can be increased (or decreased) by several factors:
#A. Weather.
On hot days, your car’s A/C system has to work much harder to keep the cabin temperature low. That means when it’s hotter out, the air conditioning puts more demand on the engine, consuming more fuel.
#B. Driving conditions.
You may know that stop-and-go traffic is less fuel-efficient than highway driving. This goes for your air conditioning, too — when you’re in traffic or driving in a city, the A/C can have a higher impact on your already-stressed engine, resulting in poor fuel economy.
At highway speeds, your vehicle is running in more optimized conditions, and the A/C won’t affect it as much.
#C. Engine and A/C system condition.
Like the rest of your vehicle, your air conditioning system benefits from regular inspections. A well-maintained A/C system runs more efficiently, reducing its impact on your engine.
An air conditioning system that is in need of repair is less efficient and can cause the engine to work harder, using more fuel.
Your local Firestone Complete Auto Care can help ensure that your air conditioning system is in top condition.
AC Usage’s Effect on Gas Consumption
So, does turning on the AC actually use more gas? The short answer is yes. When you switch on your car’s AC, it puts an additional load on the engine because the compressor needs power to run, and this power comes from the engine itself.
The energy to drive the AC compressor is typically generated by burning fuel, meaning that when your AC is running, your vehicle is consuming slightly more gas than when it’s off.
But how significant is this impact on fuel consumption? Studies suggest that using the car’s AC can reduce fuel economy by roughly three to ten percent, varying based on factors such as the condition of the vehicle, the efficiency of the AC system, the exterior temperature, and the settings used.
Heater Usage’s Effect on Gas Consumption
What about the car heater? Does the heater use gas in the same way the AC does? Since the heater typically utilizes waste heat from the engine to warm the vehicle, it does not require the same amount of direct energy as the air conditioner does.
This means that the heater has a much less significant impact on fuel consumption compared to the AC.
However, certain heater-related features, like rear window defrost or higher blower motor fan speeds, may consume more power that the alternator needs to generate and as a result, more fuel.
5 Tips to Keep Cool and Use Less Fuel
With fuel prices and vehicle maintenance cost continually on the rise, and with more than 20.1 million registered motor vehicles as of 31st January 2021, the potential for savings from reduced a/c use is substantial, not just on your pocket, but also on the environment.
Here are some tips you can use to help reduce consumption.
#1. Turn off the AC.
Decide whether you really need the AC on for cooling, if you do you adjust your thermostat settings. Aim for comfortable, not cold, this way you don’t overwork your AC and consume more petrol.
#2. Let the airflow.
Use the flow-through ventilation when you’re on the highway, and if you’re driving under 60km/h (i.e around the city/suburbs) you can wind your windows down and open your sunroof.
Manufacturers spend a lot of time & money on design & aerodynamics for a reason and If you’re driving above 60km/h windows down will begin to create drag which will consume more fuel than simply having your AC on.
#3. Use the re-circulation feature.
Use the “re-circulating” function of your a/c system. This uses less energy because you’re cooling only the air already in your vehicle, not bringing in warmer outside air to be cooled.
#4. Park in the shade.
Your vehicle will need less cooling from the a/c at start-up if it’s parked in the shade. If you can’t find a shaded area, use window shades to reduce the heat when your vehicle is parked.
Also, don’t use the a/c when you first start your vehicle. Instead, open the windows for the first few minutes and allow the hot air to escape.
#5. Shut the AC off after defrosting.
In newer vehicles, the defrost setting automatically uses the vehicle’s a/c system to keep the windows from fogging. After the windows are clear, turn the a/c off and adjust the heater settings.
When to Turn Off the AC
For maximum fuel savings:
- City Drives with Mild Weather: Open windows and avoid AC use when temperatures are moderate.
- Short Trips: AC might not be necessary for brief journeys where cabin cooling isn’t essential.
Alternatives and Comparisons
Windows Down vs. AC On – A Real Comparison
A popular debate in fuel efficiency circles is whether it is better to drive with the windows down or use the AC. The answer depends on speed:
- Low Speeds (City Driving): At lower speeds, driving with windows down can be more fuel-efficient than using the AC.
- High Speeds (Highway Driving): Open windows create aerodynamic drag, leading to increased engine load and higher fuel usage with car AC being preferable for fuel efficiency at high speeds.
By analyzing these scenarios, it becomes clearer how car AC and fuel efficiency can be optimized depending on driving conditions.
How Much Fuel Does Air Conditioning Consume According to Your Speed?
Well technically speaking fuel consumption due to air conditioning isn’t dependent on the speed of your car. But at higher speeds, the fuel consumption of a car increases. So, the part of the fuel being used to run AC is reduced.
To understand it, consider the following example. A car consumes 3 liters per hour of fuel at 30 mph. Then AC fuel consumption is about 0.6 liter per hour. And a car consumes 17 liters of fuel per hour at 120 mph. Even then car AC consumes 0.6 liters of fuel per hour.
Now using the power equation given above if we consider TOUT to be 40 degrees Celsius then PAC becomes 4kW. Since 1 hp is equal to 746 watts, hence 4 kW becomes 5.36 hp.
Let us calculate the percentage of fuel consumed due to car air conditioning at different speeds. But before that let’s fix the total power of the engine to 2000 CC or 134 hp.
Hence, you can see from the table that as speed goes up the percentage of fuel consumed for running AC is reduced accordingly.
Differences in Fuel Use by Vehicle Type
When considering car AC and fuel efficiency, the type of vehicle matters greatly:
- Standard Combustion Engine Vehicles: Most affected by the AC’s fuel draw, especially at high power settings.
- Hybrid Vehicles: These typically use electric motors for auxiliary systems like the AC, which can help mitigate the fuel impact.
- Electric Vehicles (EVs): While EVs don’t use fuel, the AC’s power draw reduces the battery range.
This analysis shows that car AC fuel consumption can differ, but its impact is always present in some form.
FAQs.
Q: Does Running The AC Use More Gas?
Running the ac uses more gas. So how does AC affect fuel consumption? An engine that’s running will usually use fuel. So when you put on the AC, the engine’s load increases. This is how it works.
The AC needs to get its power from somewhere, which obviously is the engine. This puts more stress on the engine and causes the engine to work more than required. The more the engine works, the higher fuel it consumes.
Q: How Much Gas Does AC Use While Parked?
How much gas a car AC uses when parked depends on whether the car is totally off or idle. If your car is packed with the engine on, your car’s engine is resting.
Meaning you are using little or no fuel at that point. So if at all you want to calculate how much gas you used, it will be the one you used while driving before you parked the car.
Q: How much gas does AC use when idle?
If a car is parked, yet the engine is still on, the vehicle is idle. When your AC runs while idle, you may be using up to 10% extra gas.
Say you use 15% of gas while driving with the AC on. You might be using a total of 25% together if you keep idling with the AC on.
Q: Does Not Using A.C. Save Gas?
Not using AC saves gas and, at the same time, does not. Whether or not using AC to save gas will depend on what you do with the car.
First, if your AC is off, you might be thinking of two possible options. Turn down or wind up the window. The first might cost you gas; the latter might not. But will cause more than just gas.
With the windows open, your car is exposed to a breeze that causes resistance. The engine, in turn, works to pull through the resistance so your car will run properly. This action stresses the engine and causes it to use more fuel than usual.
Even worse is if you are driving at a very high speed. More speed, more resistance, more work on the engine, more fuel.
If your windows are opened, the best practice is to drive slowly – you consume less fuel.
Then you may ask, what if I decide to wind up the window with the AC off? It causes your cabin to heat up. The heat could cause serious health issues or result in suffocation or drowsiness, which could lead to a crash.
Q: How Much Fuel Does A Car Use Idling With AC On?
If you leave your car idle with your AC on, you will be using between 8% to 10% extra fuel.
While it is true that you consume fuel when driving with your AC on, you tend to use more fuel when idling with AC on.
Even a Toyota Innova, which doesn’t consume fuel with the AC, is affected by such idling.
Q: What Uses More Fuel, AC, Or Windows down?
Both methods use fuel. And I guess you would probably think your AC consumes more fuel than the window down. To others, having windows down is a great way to have better gas mileage. But which method consumes more fuel depends on your car, driving habits, and many other factors.
In some cars, driving at high speed with AC on is fuel-efficient. But at low speeds consumes fuel. In reverse, moving with the windows down at high speeds consumes more fuel. But low speed saves gasoline.
In other words, none consume more than the other. It just depends on your car type and what you do while applying either method.
Final Thoughts
Driving in a cool car during a hot summer makes driving comfortable. But many still want to know how much gas is at risk here and how it tells on their pocket. So they ask, how much gas does AC use?
This question helps one decide whether to use the AC or opt for other ways to cool their car. However, whatever method you use will still use gas.
Adopt the one that is good in your pocket, considering your car brand and other factors. Windows open on low speed or AC on high speeds are good options.