The a/c in chevy sonic fluctuates about 40 and 60 as the compressor goes on and off. Is this normal to fluctuate so much. The 50-60 is the yellow zone on my gauge and anything above 60 is red. Based on temp, the proper range should be 40-50.

I wouldn't worry about that as long as it is cooling.

Are we playing with a new tool or vehicle?

I was measuring the pressure using a gauge that was attached to R134a canister that I had used up last year.

The pressure fluctuation was on 2014 Sonic 1.8L