[ingalmi]

So let me amplify my earlier remarks;
Some Montana models come with provisions to add a 3rd A/C unit normally by removing the ceiling fan in the kitchen area. The wiring is pre-wired for both 115vac and the thermostat. However the 3rd A/C unit will share power with the bedroom A/C unit through a power shed switch which is located in the basement behind the soft removable panel (same area as the heater and hot water heater.
The only way to have all 3 A/C units running at the same time is to remove the 115vac feed for the 3rd A/C from the power shed switch and route it to the breaker for the dryer (if you’re not using a dryer). Or...... use the power shed switch to control the dryer and 3rd A/C. Dryer on no 3rd A/C, 3rd A/C on no dryer. Bottom-line it’s doable and plenty of power. I do it all the time.