How do I know if my AC capacitor is bad?

The most common signs and symptoms of a bad AC capacitor include:
  1. AC not blowing cold air.
  2. AC takes a while to start once you turn it on.
  3. Humming sound coming from your air conditioner.
  4. AC shuts off on its own.
  5. AC won’t turn on.

How do I test an AC capacitor with a multimeter?