My Wagner 2 hp well pump runs for only 30-40 seconds then blows breaker, was running fine last week. Is it the capacitor or something more serious?

the thermal circuit breaker is overloading
that can be from a faulty tcb or a problem in the compressor ( seized)
most need start/run capacitors for the motor to start and if it / they are faulty then that will blow the TCB
if it has 2 capacitors ( one for start which it is doing and the other for run then that capacitor may be the problem
if it has the one unit with 4 wires , replace the capacitor
suggest that get an electrician in to check out the unit

Need more info. What is the voltage at the pump? What voltage is the pump wired for? Sounds like your pump is shutting down from heat thru a safety. If the voltage is wrong the pump will heat up very quickly and a thermal switch will cut out, it will then cool off and try again. Get the readings at the motor connections NOT the breaker.

could have a bad run capacitor or a start capacitor . search your area for your local pool pump motor repair guy with free testing, 9 years old that motor needs to be rebuilt.. i charge 85.00 to rebuild a 2hpincludes a free shaft seal.. remember to prime the pump with water after a repair !! best of luck .. oh breakers become week after amount of time time .. and ask the repair guy if this is the right size pump for you pool.. 9 out of 10 times its way too big !.. jay longwood florida

faulty start/run capacitor

might be the starter capacitor or run capacitor

Sounds like a wiring problem between the outdoor unit and the house. You would be surprised what I have come across in 30+ years of A/C work.
But it could also be the compressor.

I will need to know answers to the following -

Does the compressor have a soft start (2 wire capacitor looking device that attaches to the run capacitor), hard start (relay and capacitor), or just the run capacitor?

Were the run capacitors and start components replaced when the compressor was replaced?

Is the breaker a GFI breaker, or just a standard breaker?

Rain or humidity is not usually a factor, but it may be something.

Reply back what you find.

Bad fan motor