The amps that your air conditioner uses should be located on a label on the side of the air conditioner somewhere.
It should list the voltage and amperage as well as the model number.
Most central air conditioners use 12 to 25 amps when running continuously while but when starting they can draw up to 50 to 60 amps.
Window air conditioners such as the small window air conditioners may only use 1 to 3 amps of electricity and may draw 12 amps or more when starting.
A 1.5 ton AC uses between 8.5 to 12 amps of power when running continuously.
However when the 1.5 ton central air conditioner starts up it can draw as much as 50 to 60 amps of power to get it started.
The 1.5 Ton central air conditioner has a large compressor that needs a lot of amperage to get started so it has an electrical capacitor on it.
That capacitor stores electricity to allow the compressor to start and so the ac can draw up to 50 to 60 amps.
When my central air conditioner starts up it draws 50 amps and will dim the lights slightly when it starts but then after it's running it draws only 12 amps continuously.
You need a large enough breaker switch or fuse to carry the current that will go through it when it starts.