Look at the manufacturer's plate on the AC for a "fair" idea what the start up amperage will be. Look for something called LRA
That is Locked Rotor Amps or the amount of amps the compressor motor will pull at a dead stop. Once it starts turning the amps will drop to its operating amperage.
Column-by-Column: Locked Rotor Amps and KVA | Franklin AID
My LRA is 58 amps but the compressor will begin to turn almost immediately and my ammeter display is not instant so I get an average over the 1 second sample time.
RLA: Acronym for "rated load amps". The maximum current a compressor should draw under any operating conditions (running on speed). Often mistakenly called running load amps which leads people to believe, incorrectly, that the compressor should always pull these amps. You should never use the listed RLA to determine if the compressor is running properly or to condemn a compressor. The running amps of a compressor are determined by the evaporator temperature, condensing temperature and the line voltage.
FLA - Full Load Amps: Changed in 1976 to "RLA - Rated Load Amps".
That is why some folks have no trouble with their generator and others can't get it to go. Air temp, humidity, and line voltage play a big role in whether your Generator can turn the beast over.
Some generators are more sensitive to overload than others as well and may drop off line quicker than others.
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