Our air conditioner circuit breaker marked "AC", is tripping frequently after the AC unit works for a while. Sometimes as long as an hour or more and, sometimes as short as few minutes. We were told the AC motor needs to be changed, but we decided to change the whole unit, since it has been 14 years since we bought the house. But the same problem persisted with the new system. The people who have installed the new AC, have been checking to make sure there are no blockages in the refrigerant lines. still, the problem has not gone away. What are the possible causes, remedies, and safety precautions I should consider in this situation?