Shut the circuit breaker off in your main electric panel.If you're not sure which circuit breaker your air conditioner is connected to, shut them all off. There may be more than one breaker involved. Make sure the power is off before working with any air conditioner. Take the door or cover off of your unit's control box and. You'll need to discharge the run capacitor and make it safe for further check up. Discharge the capacitor by using a very well insulated tool such as. If you have a dual-rated capacitor, you'll see three terminals marked Herm (short for “hermetic,” which indicates that the compressor is part of a hermetically sealed system), Fan (may. When you've checked everything out and you're sure that one or both of the capacitor's values are not near the appropriate requirements, it's necessary to change it. There are two.