
It may sound like an odd question, but its one that does get asked.
The answer is Yes, but I will explain why the answer is yes.
The air conditioning, automatic air conditioning, air con, aircon, A/C or climate control found on the Citroen C3 all work in a similar way and are used to reduce the humidity of the air in the car which lowers the temperature in the cabin.
There are many advantages to using the air conditioning, even in the winter;
Windscreen Demisting:
Reducing the humidity, removes the moisture in the air, a quick way to demist the windscreen is to use the air conditioning on high fan rate, maximum cooling, directed to the windscreen. This method for demisting actually removes the moisture from the screen without smearing and doesn't require engine heat that the 'heater on max' method requires.
Driver Comfort:
A cooler cabin on a hot day makes for a more relaxed drive. The air conditioning reduces the temperature of the air in the car keeping the occupants cool. Opening a window lets air into the car from outside with the associated wind noise and buffeting at higher speeds. The cooling effect you get from opening a window is mostly from a wind chill factor.
The Citroen C3 can be fitted with a cabin filter, also known as a pollen filter. The air that is cooled by the air conditioner is first filtered by the cabin filter to trap pollen and small particle contaminants, but opening the window bypasses the filter and lets the pollutants into the car.
A Citroen C3 cabin filter is shown here:
citroen-c3-tips/citroen-c3-pollen-filte ... -t244.html
Like any filter, its gets clogged up over time as it collects the particles it traps. The solution is to replace the filter with a new one from here and it easy to replace, just follow these instructions to change the Citroen C3 cabin filter.
A 'recirc' button is found on some systems to activate recirculation. Which reuses the air in the car rather than drawing air from outside and through the cabin filter. This is useful to stop smells from entering the cabin or clogging the filter if you are passing a very dusty area. It is not recommended to recirculate the air for any extended period as the air will get stale because no fresh air is entering the cabin.

Economy:
At higher speeds having a window open creates drag on the car causing the engine to work harder and use more fuel than if all the windows were closed. Having the air conditioning 'on' does use more fuel than not having it on, but less fuel is used with the air conditioning on than from the extra drag created by open windows at speed.
At lower speeds, having the windows open doesn't create much drag or wind resistance on the car so no more extra fuel is used, but having the air conditioning on at low speed will use a bit more fuel than not having it on. So the only advantage to not using the air con is at low speed driving, but Driver Comfort can be compromised with the window open.
Maintenance:
The air conditioning system is run by a pump and a clutch. The pump is not running unless the a/c button is activated in the car. Pumps benefit from being used because this keep the pump seals lubricated. Its recommended to use the air conditioning once a month for a few minutes to ensure the pump gets used, this helps to move the lubrication around the system. Even in the winter the air con should be run to keep things running smoothly for the summer, as mentioned above, the air con is also be very useful in the winter.
Tips:
If the car has been parked in the sun and you return to a very hot car, firstly allow the hot air out of the car, open the windows and drive off. This allows most of the very hot air out of the car. Within a short distance close the windows and activate the air conditioning or climate control. With most of the hot air removed, the air conditioning has to work less hard to cool the car, saving fuel and wear on the components.
The air conditioning takes its power from the engine, more air conditioning uses more fuel. Don't have the car cooler than you need as you will be wasting fuel (petrol or diesel).
For the air conditioning or climate control to be effective the windows need to be closed. If a windows is open and the air condition is 'on' you will be running the pump more than necessary, causing more wear, using more fuel and not cooling the car as much as you like.
If the air conditioning is too cold, turn down the setting for temperature or fan speed, or both. Altering the direction of the cool air (windscreen, face, low and feet) can make a difference to how cool you feel without changing the fan speed or temperature setting. Having very cold air blowing in your face can feel quite harsh, try deflecting the air off the windscreen or direct the face vents away from you. Cold air on the feet setting can feel great for those with open toe shoes on a hot day.
During a run, opening a window or door will allow unconditioned air into the cabin which will require air conditioning to reduce its temperature and humidity, using more fuel than was originally required.
If your air conditioning doesn't blow chilly air out of the vents when its activated, you may need to have the refrigerant recharged. Its worth having this done every few years as it doesn't appear in the service schedule, costs about £50, takes about an hour and can give you a lovely cool drive back from the garage. F1 Autocentres (book online here)
DIY or home kits to replenish the refrigerant in the C3 A/C system but they shouldn't be used if there is a leak of refrigerant as this needs a repair. It is always advised to get the air-con system professionally serviced because of the environment damaging gasses used in the process. It is not permitted to let the gas escape into the atmosphere and the experts in car a/c can do it safely.
UV dye or an Ultra Violet dye is often added to air conditioning systems to
aid the detection and location of leaks. If the system contains a dye and subsequently leaks the location of the leak can be shown clearly with a UV light detector torch on Amazon