How well does your electrical system work? You might not notice any major problems, but do you experience your lights dimming when your air conditioner turns on? If that is the case, it is a sign that your circuits are overloaded. It might be that you could easily solve this problem by moving your air conditioner to a different outlet, but that is not always feasible. What if you have breakers tripping regularly?
While that too might be a sign of an overloaded circuit, it could also be due to a malfunctioning appliance. If you want to know for sure what causes your problems, you will need to do some detective work over a period of time. Plugging appliances into circuits that are on a different breaker or just leaving them unplugged will show if they are causing the problem.
While you might be able to figure out the problem on your own, your only solution might lie in contacting an electrician.