The repair time for your air conditioning machine may vary depending on the problem.  If the problem is as simple as a flipped emergency switch, it can be diagnosed and repaired in under an hour.  Low refrigerant in the unit can be resolved in a matter of hours.
Other issues, on the other hand, may take much longer.  A malfunctioning compressor, for example, can take a professional all day to repair.  If there is broken ducting, the project may take many days to complete.  This is why, if your air conditioner starts producing strange noises, you should have it looked out.  Something that starts out as a minor problem can quickly escalate into a major one.