If you've noticed increases in your energy bill, but have not changed your thermostat settings or usage habits, it could be because your air conditioner is broken and struggling to operate efficiently. 

While your AC unit isn't exactly designed to be silent, sudden grinding, buzzing, or rattlings sounds may be a sign that your unit's internal components are broken. 

Short cycling occurs when your unit starts and stops in rapid bursts, and is a common indicator that your air conditioner is broken. Your system should normally run in cycles that last long enough to keep the temperature steady. Short and frequenet cycles wear down components, use more energy, and make the home uncomfortable. 

When your air conditioner is operating properly, it not only works to cool the air but also removes humidity. If your home feels muggy even when the AC is running, your air conditioner might be broken and no longer properly managing indoor humidity levels. 

Different odors from your system indicate specific problems that often precede failure. Musty smells suggest moisture buildup and microbial growth in your system or ductwork. Burning odors often indicate electrical problems, while chemical smells might point to refigerant leaks, requiring immediate attention. 

Some condensation is normal for air conditioners, but visible water pooling around the indoor unit is a signal for trouble. Proper AC operation should direct most condensation outside through the condensate drain line.