Upon arrival, the customer explained noticing a water stain where the primary drain line set goes through the plywood box The unit sits on. I checked the drain line. It was clear. I went ahead and flushed it anyways checked the customer‘s pressures. They looked good. The coil was clean. The primary pan had no trash whatsoever in. It was absolutely spotless. I let the customer know that whatever the water stain is from is not leaking because the wood was dry and it wasn’t wet and soft. And that it could possibly be from spilling a little water to flush the drain line the only other thing it could possibly be is if the indoor blower motor is intermittently stopping and causing the coil to freeze up. I told the customer if she notices it again to take a picture and give us a call back. She also mentioned having a dust issue inside so I sent an estimate to get her ducks cleaned and checked our UV light. The UV light is working properly. Everything seems to be working properly at this time.