Performed ac diagnostic York rooftop package unit. Found system running on arrival then while I was in front of unit it tripped. Checked the fuses in the disconnect max fuse size 35, and they are 35 amp fuses. Ok. Then checked and tightened all power wires and went to go look at breaker panel. found 40 amp double pole Zinsco skinny breaker. Missing the bar between the legs of power. When I pulled the panel found a wasp nest inside of unit. Need to remove wasp nest to test system, and test breaker more. Clients boyfriend helped me remove wasps. Then checked and tightened connections. Went back up on roof and tested system, running at 10 amps nowhere near enough to trip breaker. So my conclusion would be wasps kept tripping it. If problem happens again recommend replacing breaker with new Zinsco skinny 2 pole 40amp.