Residential warranty. Arrived to find no sound audible in master bathroom wall or at sink. Removed some water from system p-trap and re-energize the system to find small gurgling sound coming from the bathroom sink that may become louder the longer the system remains off. Re-leveled primary condensate drain line to allow proper function of the p-trap. Primed condensate line with water and tested at high cooling speed to ensure no sound was heard at sink. Systems operating properly at this time but instructed homeowner to please record the sound and the exact area in a video to send to us if it occurs again and we will come out to reassess.