I am working with two other guys in same room. I have a problem with one who started working lately with us. Air conditioner is adjusted to 22 Celcius by me and other guy in consensus then this guy comes and increases it to 25 Celsius even without asking any of us like he behaves as if he is the sole owner of the AC. How do I deal with this kind of behaviour? I also sensed he is trying to provocate and forces us to do an angry move but we are not people like that. How should I approach this?
Embrace the power of cool.
Don't make a big deal out of it - talk to the guy and discuss a possible solution to the problem. Don't buy into his negative attitude, act like it's not there. Go for the compromise and set the temp to 23,5'.
If all else fails - you can try to change your working space or try taking it upstairs (which I don't recommend).
I'd like to offer a more general perspective: there are quite different standards of preferred AC in different regions of the USA, in Europe, and in Japan. Generally, US < Europe < Japan in terms of desired AC temperature.
In the US I encountered cases quite a few times where people would carry jackets with them in 40+ degrees (C) temperature outside, because they had to put it on inside, at a temperature of 15-16 degrees (C).
In this situation, as a European, I got (once seriously) ill a few times, due to these temperature differences (despite jacket); so there is a serious health aspect to having the temperature that low inside (apart from the energy wastage, but that does not seem to be an issue in the US). Airconditioned indoors climate is not equivalent to outdoors climate at 15 degrees even when jacketed, plus one is exposed to it for prolonged periods while sitting a chair.
So, wherever the AC discussion starts, it should be kept in mind that it is not just one party who is uncomfortable at higher temperatures, but also the other one who might get ill at lower ones (despite clothing up!). The choice between who is going to be uncomfortable and who is going to get ill is what we are discussing here and empathy should go both ways.
Speaking of discomfort, it is also not clear why, during summertime, when one should be able to travel lightly, people should have the discomfort of carrying around pullovers and jackets with them by default to counter an overzealous AC (assuming it is enough to combat the AC effects).
That being said, in the present's OP case, 22 degrees would probably be reasonable even for Europeans (but perhaps not so for Japanese, who prefer higher temperatures).
As consequence, I suggest you take into account that there is a - possibly serious - reason for your fellow worker to prefer a higher temperature and discuss with them a compromise. By ignoring their position, even if you manage to impose your preferred temperature, you may be putting their health at risk (which also may explain their unhappiness in that matter).
I had the same problem once in a small office where we all had a room. We solved this problem rather easily by purchasing magnetic vent covers, and the person who is too cold simply installs them partially, or completely over the vent in their office to control the amount of cold air entering their space.
Just talk to them about it
We had a similar issue at my work and resolved it by talking about it. People who felt cold simply brought a jacket to work or switched desks to sit near a window, in the sun, or away from an AC vent. Basically, if you just talk about it I am sure you can compromise and come to a resolution. It is important to recognize that while they are not the sole owner of the air conditioner, neither are you.
It basically comes down to most simple workplace problems, if you talk about it and are respectful, 95% of the time you can find a solution where everyone is satisfied with the outcome.
Others have addressed how to handle this guy, but I just wanted to add that when it comes to comfortable office temperatures it's best to go on the cooler end of the scale.
It's easy to put on more clothes. Long sleeves or an extra layer. It's harder to take clothes off and cool down beyond a certain point though. Therefore people who prefer an abnormally hot environment can easily accommodate others, where as the opposite is not true.
I would consider discussing it with your Manager, if this coworker is not willing to listen or compromise. Tell them that you are concerned it is leading to tension in your workplace. Hopefully your Manager will then discuss with everyone involved and define a clear policy for how the AC level should be set, which should put an end to the arguments.