The fact that the furnace is 6 years old, there's a 100% likelihood that it's a high energy furnace with no chimney but utilizing PVC piping, the "rain" is more than likely condensation which the new furnaces produce. I'm also thinking that since this person posted this several month ago, the problem has since been resolved and the tech found a malfunctioning CPU.
I know how to bring out the buffoonery of A Trump supporter.State Fact