The air conditioner capacitor is used to sustain voltage and start the cooling system's motors. The air conditioner's capacitor drives the air conditioner's motors. Thus it's also required for it to work. In addition, air conditioners often include three engines, all caused by the capacitor. As a result, if the capacitor isn't working. Step 3: Remove and Replace Fuses. Start with your underhood fuse panel. Make sure that you can see your multimeter while you pull fuses. Use your needle-nose pliers or a fuse puller to remove and replace fuses, until you see the Amps on the multimeter drop. Be careful that each fuse goes back into the correct location.