Upon my arrival I found two supply vents sweating in the loft area. I personally witnessed the access to the attic was open I made customer aware that was a very good possibility of why the vents are sweating due to mixing hot air with cooler creating condensation. Customer is adamant it is because of the two ducts are not sealed however I inspected all the other ducts on this system and none of the other ducts are condensating. To satisfy this customer we will need to return with a tube of caulking or silicone and caulk behind these two vents that is her request. I personally do not have any sealant on my van so we will have to return for service.