That's for a belt-driven A/C, tied directly to the engine RPM. They're inherently much less efficient because they have to work over a wide range of speeds. A motor-driven A/C will be 1-2 kW.
That's also the peak power, and a motorized A/C will instead be turned on and off leading to a much lower power draw that also depends less on the peak power. Typically a 50-30% duty cycle, so 200-300 watts very roughly. More depending on the insulation, sun, and outside temperature.
And if instead of getting into a sweltering 330K car, if 300W was enough power to cool it to a reasonable 300K, that's still a win. Happy to start car to cool it down to a comfier 295K.
Window units range from 700 W to 2+ kW. The Model 3 has a pretty powerful one, at least 1 kW. That's peak draw, and it'll turn on and off intermittently[1]. Average draw should work out to 200-300 watts for medium.
[1]: Like a fridge. Refrigeration systems are most efficient at full power. IIRC it's due to the restrictor plate separating the hot and cold radiators- it's designed to work at a certain rate of flow, so you'll get gas and liquid mixing at lower power.
This probably isn't the most reliable source, but the infotainment screen on my VW estimates the hourly gas consumption for the climate system.
Running on Max A/C, the screen reads just under 1/8 gal/hr. With the A/C on and with the fans at 50%, consumption is a little less but still around 1/8 gal/hr. Consumption drops too low to get a reading when A/C is off with fans 50%.
I'm actually not sure in terms of car AC. Local wisdom says that on hot days your AC will sap up to 10 HP from your engine. Not sure how accurate that is.
Looking around on Telsa forums and the like, I'm seeing numbers between 1 and 3 kW. My house's mini split AC unit draws around 9 amps (according to documentation, anyway), so around 2 kW. Actual numbers seem to be closer to 3 kW in the summer.
I currently have my Tesla plugged in to my 6kw home charger, with the AC blasting, and the range isn’t increasing, leading me to believe that the AC running 100% takes around 6kw.
Oh man passenger reactions would be so awesome. Suddenly the driver just says "divert life support to propulsion" - and the passengers are like "WAIT WHAT LIFE SUPPORT?!"
