Let's face it, a lot can go wrong with your residential AC system over the course of its lifespan. Your refrigerant might start leaking; the condensate drain line can overflow; the air ducts can get clogged; your compressor might fail; or perhaps the unit that was installed is too small for your space. More often than not, there are obvious warning signs when an air conditioning system is not working right. But sometimes, the indications of a problem are more subtle, or there's no sign at all before a sudden breakdown. Knowing what to look for will help you know when to call a professional before the problems get out of control. Common signs that your A/C needs repairs include: Not blowing cold air Weak airflow Malfunctioning thermostat Excessive moisture or leakage Unusual sounds Foul odors Low refrigerant levels Increasing energy bill Learn how to troubleshoot common A/C issues that plague homeowners.