When you press the power button once (or twice?) without holding the brake, it should initiate the 12 battery and not engage the HV traction battery. I estimate the draw from the 12v to be at about 70 watts from just doing nothing but running the fan. I installed a charger port to the 12v battery with a voltage indicator. This should allow me to run the fan indefinitely (while the sun is out) if I have a solar charger powerful enough to keep the 12v battery topped (about 70 watts solar charger). For now it's there for emergency 12v charging without opening up anything but the light cover door.
If you engage the HV traction battery, the energy draw is about 200-300watt. Just to have the fan running. Based on Dr. Prius energy app readings. But the engine will fire up to recharge the entire system. AC draw about 700-800watts.
The A/C compressor is variable speed. In a Gen 3, it can draw anywhere from 250 watts to 2500 or so, depending on conditions.
