When your air conditioner is running, your outside unit, the condenser, should be dripping. If the condensation line isn't flowing, the unit will stop. In addition to adding vinegar, take your shop vac outside by your condenser, and vacuum out your condensation line. This should be done at least once or twice a year.
Following these steps will help to prevent your HVAC from failure. A clean, properly functioning HVAC unti will keep the air in your home cool, clean and comfortable.