Circuit Breaker Keeps Tripping?

I have just bought a 1966 mobile home. It is a 2 bedroom, 1 bath with 2 breakers, 1 in each bedroom. There has been some remodeling done, new bathroom lights put into ceiling, in living room overhead light, in kitchen it has a double oven built in. The 1 circuit breaker runs the bedroom, kitchen, dining room (both kinda like one room), the 2nd circuit breaker runs the other bedroom, bathroom, laundry room, living room, and front porch light. There are also 3 air conditioners, 1 big old one in the bedroom of the 2nd circuit breaker, 1 newer small one in the living room, and 1 big one in the dining room. The circuit breaker in the bedroom that runs kitchen etc. seems to work fine, but the other one that runs the living room etc. keeps shutting off. It seems like if the big old air conditioner is on and all lights are on it shuts off within maybe 10 minutes. I think it's longer if the old air conditioner is off. There is nothing plugged in except air conditioners and overhead lights and stove, no refrigerator. Just don't know if it's the air conditioners or something within the remodeling.