Unit keeps tripping the circut breaker. I reset the breaker and in 15 minutes time it trips the breaker again

Tripping can be due to over current drawn by the compressor .This can happen due to lower voltage prevailing during that period (due to several other electrical appliances being connected on the same circuit etc).The condensing unit may be accidentally covered by an obstruction (eg cloth, carpets, polythene film etc).also it can happen due to the out door unit (condesing unit) fans not working .Check the cool gas line from evaporator(cooling coil) to the (out door ) condensing unit.If this with an ice covering check your return air filter for excess dirt and correct it. ask the service man for the running current reading he got and compare it with that on the name plate ..Best you ask him to fix ammeter and take readings at regular intervals through out the day.That will give an indication.The circuit breaker itself may be defective.The amp test above will tell you that too.