Came out to call for a mini split system leaking water onto his stairwell. Customer stated that he looked into it and found that it could be the drain line clogged. I checked the drain and found a hornets nest near the drain coming out of the wall. After I sprayed the nest, customer wanted the drain line vacuumed out. I cleared out drain line and tested drain to verify it was working properly. Customer stated he could hear the clog clear inside. Recommended that customer used diluted cleaning solution like bleach to help keep the drain clean. System is no longer leaking water inside home.