If your air conditioner has all of a sudden decided to stop working, it could be due to many things. Some things are very easy to fix so you could have a quick solution. Below are two common things that may be wrong with it.
Not Coming On
If your air conditioner is not turning on, this could be a problem with the breaker itself or the breaker may not be turned on. Go to your breaker box and see if the breaker is turned off. If it is, it could have had a type of power surge that tripped it. Turn it back on, and then turn your air conditioner on. If it will still not come on, the breaker could be bad. If you are not sure how to tell if the breaker is bad, contact an electrician to help you.
You should also check your thermostat to make sure it is set properly. Lower it down a few degrees and see if that kicks your air conditioner on. If it will still not turn on, the problem is something much more serious, such as a faulty compressor or motor.
Noisy Air Conditioner
A noisy air conditioner could be due to many things. First, determine the type of noise that you are hearing, as it could tell you what is wrong. If you hear a screeching or squealing, this could be a motor bearing problem, or a bad belt on the air handler. Belts are easy to replace if they break. Your motor may simply need to be lubricated. Refer to your HVAC unit's user's manual to see what type you should use, and where you need to place it.
If your air conditioner is banging or rattling, this may be a problem with the motor or blower assembly. This means something has come loose inside the unit. A very loud banging sound means something has disconnected or broken loose completely. Turn off your AC unit before more damage is caused.
If you hear clicking sounds, this is normal when you first turn the unit on. If you continue to hear the clicking sounds, however, you may have a defective relay. There also may be an electrical problem causing the relay to fail or timeout.
If you continue having problems, contact an HVAC business, such as Daryl's Heating & Air Inc, to come to your home to determine what is wrong with your unit. While they are there, have them do maintenance on your system to ensure it continues to work well for you.