The most common cause of ac leaks is a clogged air filter. Dirty filters slow or stop cool airflow, preventing refrigerant from moving through the system. If thatÒ€ℒs the case, the refrigerant can freeze your systemÒ€ℒs evaporator coils, and water will Ò€¦ most ac systems feature two drain pans to catch condensation under the air handler, the indoor unit is usually installed in an attic, basement, or dedicated closet.