My thermostat has the ability to set each AC unit to LOW, HIGH, and AUTO. If you set each on to either low or high the fan will run continuously. Mine is a Duotherm system.
I think the problem with your that a 30 amp system will not support running 2 AC units so one is being shut down by the EMS system.
I have a 50 AMP system but if I am hooked to a 30 amp source the EMS system recognizes this and allow power consumption up to 30 amps before shedding. I have 4 circuits that are shed, AC1, AC2, Water Heater, and Washer/Dryer. I can run 1 AC unit at a time on a 30 amp system and then have to watch other loads, if we use the microwave the AC unit will be shed.
2002 Monaco Windsor 38 PKD
2005 Jeep Grand Cherokee w/5.7 Hemi