- Seal all connections w/waterproof duct sealant on RTU number 11. Diagnosed RTU number 18, no issues with the system. Diagnosed RTU number 6, system only running at half capacity on circuit number 1, circuit number 2 off on low pressure. Found that circuit completely empty of refrigerant. Performed leak search and found leak at evaporator coil. Gave client option to replace coil, however, recommend replacing entire system due to age and cost of repairs. Laura will review options and get back to us on which option she would like to move forward with.