Air Conditioner blows hot air

There are many reasons the compressor may not be working, low refrigerant level, bad low pressure switch, faulty compressor clutch and a few other voltage supply issues. If the compressor was cycling on and off a lot, then it is likely low on refrigerant and you can try adding some refrigerant to see if that helps. Ideally you want to check the voltage supply to the compressor and follow it back to the a/c switch to see why it isn't working. This will help to figure out why the compressor isn't working.