In some cases, a malfunctioning air conditioner is a minor inconvenience. In other cases, it can be the difference of whether you can stay in your own home or you have to temporarily stay somewhere else that has a working air conditioner. For example, if the air conditioning goes out in the home of someone who lives in a hot desert region during the summer, then this can create a very dangerous environment where those in the household can be at a significantly increased risk of heatstroke. In this situation, you want to call out a technician on an emergency call if this happens after hours. There may be other things that can also happen that can constitute an emergency. Here are some examples of these types of things and what you want to do if one of them is going on with your air conditioner.
There is a refrigerant leak
If your air conditioning still sounds and blows like it is working, but the air coming out of the vents is not cool, or it isn't as cool as it should be, then you probably have a refrigerant leak and this is something that is considered to be an HVAC emergency. You want to turn the system off until the problem is fixed and the tech has added more refrigerant to the system.
There is a clogged condensate drain line
Another thing that is considered an emergency is a clogged condensate drain line. Some signs of this problem include water dripping in or around the air conditioner, water damage near the air conditioner, a drip pan that is full or water, or mold is found near it. Once you suspect this, stop using the unit until you are able to get HVAC repair.
The air conditioner has frozen
If your air conditioner stops blowing cool, then the air conditioner may be frozen. Look to see if there are signs of ice on the tubing which will be easy to recognize when you see it. If it is frozen, turn it off and allow it to thaw all the way before attempting to use it again. If the issue happens again, then you want to make a call for someone to come out right away for an emergency visit.
There is an electrical issue happening - Any time there is an electrical issue in your home, it is an emergency and its the same for the air conditioner. If you suspect you are dealing with electrical issues, turn the system off, unplug it, and call for an AC emergency visit.