You can't run the ac without running the car.
Your car's AC is powered by the serpentine belt, which wont be moving anytime the engine is off.
Both statements above apply to typical ICE powered vehicles. Most newer HYBRID vehicles use an AC powered compressor via battery bank and inverter controls. So, if you had a decent solar array and batteries ($$$$), you could theoretically sit in your hybrid car for hours. For pure ELECTRIC (TESLA and more $$$$), some tests indicate the AC could run for up to 100 hours without recharge until it shuts off at a programmed 20% battery level.
Best bang for the buck (low initial investment, high short term reward), I would second a small room with small window unit, powered by an inverter technology generator that is itself powered by natural gas, LP/propane, diesel and/or gasoline. Lower initial investment designed for intermittent use, especially in places like California with rolling brownouts. There is no inexpensive means to currently provide AC to a whole house.