By resetting the power you will only temporarily clear the fault until system comes back on and it senses once again a faulty high pressure sensor, hence why it cuts off after a few minutes as you have described. My advice is either : getting the installers to have a look at it as its only been installed a year or so, test the transducer as i previously said OR get a specialist to come and diagnose the problem. If its a problem with the refrigerant gas side of system then you will need to be F-Gas registered to work on it.