Good evening, capped capillary is not, when the capillary is capped the low pressure that should be between 60 and 70 psi will be lower than usual, in your case it is the opposite, the pressure rises while the compressor is on, I suggest First check the connection of the cables in the compressor and its capacitor, you must correctly identify the three terminals of the compressor, one is common, another gear (work) and the other is start, the two phases that feed the compressor must go to the Common and Work terminals, the cable that feeds the starter must be with the capacitor, and in turn, the phase that feeds the capacitor must be the same phase that feeds the Work terminal on the compressor; If the compressor is installed correctly with its cables and the capacitor, and still the problem persists, then it is the compressor that has problems with its internal mechanism, suddenly stopping compressing, there are many cases like the one you mentioned, the compressor can work well a few minutes or even hours, but suddenly it decompresses and stops compressing the refrigerant gas, in this case you must replace the compressor.