This appears to be either the compressor or the fan overloading the circuit breaker. Either this, or the water heater is pulling too many amps to allow for the AC to run properly.
Since you did not indicate whether the AC and W/H are on the same breaker, I don't know if the main breaker or a single circuit breaker is being tripped.
Check the hub for how to check how much amperage is being required by the AC unit. Good luck on finding the problem!