If that doesn’t solve the problem, locate the drain line access point near your indoor air handler. If your system's designed properly, there is a primary condensation line. AC /heat pump check 1st floor Ac heating, Heat pump, Heat How to clear a clogged air conditioning drain line ugly duckling attic air conditioner drip pan installation hvac coil catch drain lines chion forest air conditioning heating inc How to clean ac drain line in attic . This helps protect you from ending up with a full ac drain pan or one overflowing with water. What you'll need to do is brave your attic. By pouring a ¼ cup of vinegar into your ac’s drain line, you will kill any mold, algae, mildew, and other forms of bacteria or fungi, preventing it from forming a buildup and causing a clog. Turn off the power to your hvac system at the thermostat and at the breaker. How to clean an ac condensation drain line. Central air conditioner evaporator coil cleaning. | ac drain line clog...