How are you determining the amp draw? From the onboard EMS system? If so, that is pretty accurate. Are you on 50 amp service. I ask, because some EMS systems will shut down the compressor(fan stays running) when you pull more amps than can be supplied(30 amp service). If you pull 15 amps, that indicates the AC units are fully charged. I assume since you have the Drain hoses, you have RVP/Coleman AC units. Since you have RVP units, each unit has a water drain pump to pump the condensation out the drain lines. When the Drain system fails(clogged or the pump fails), then the water comes off the roof. I would suspect that in the past 10 years 1 or more of the AC units has been replaced or pulled for some service work. Inept Service Technicians usually FORGET to install the Divider GASKET that separates the Intake from the exhaust when replacing the upper unit on a top mounted bolt down unit. This will result in a severe lack of cold air volume into the roof AC ductwork and will cause the Freeze sensor to trip prematurely and cause a lack of condensation. The Best way to determine if this is the case is to pull the AC unit and verify the Gasket is installed. 3 AC units(ducted) should freeze you out in 85/90 degree weather. Doug