House AC went out can I hook up to 20 amp gfci

Usually on a 20 amp (T-shaped neutral) circuit you can run 1 "Big ticket" item (A/C, Water heater, Microwave) as others have said run the fridge on Propane
And make sure the batteries are full (Give them at least 2 or 3 hours of "plugged in" time before you run the A/C)

Of course this only works if your spouse is not Eva Gabor (Reference to TV show: Green Acres)