I've got a 4 y/o Carrier AC unit that worked fine all summer (bought the house this past winter). Today, I noticed that the house isn't being cooled, and the AC is making a loud buzzing noise. The noise is periodic - roughly ever 3-5 minutes, and lasts for about 5-10 seconds - like something's trying to start and failing. The condenser fan spins the entire time, but appears to do so more slowly than normal, and - no cold.
Could this be a capacitor issue, or should I call in a tech?