Good, you must first check the filter drier, it may be clogged. We will proceed like this: with the OFF air you connect the manometer to the high clock you connect it to the high valve and then turn ON the air conditioner and connect the low clock and wait for a while and observe the 2 pressures and locate the filter dryer and you feel by hand its temperature on the inlet and outlet of the dryer filter and see if there is any temperature difference and this operation is done several times in a period of time and after a while you observe a temperature difference between the entrance and exit of the filter, that is indicative that it is clogged. check the entire pipeline high and that it is not bent or broken. check that the 2 keys of the load valves are open (Allen keys). make sure that this condensing unit is an expansion in the condenser or an expansion in the evaporator. if the expansion is in the evaporator there the high pipe if it must be hot. if the expansion is in the condenser, the thin pipe should be cold and in this case it would be called a liquid or pre-expanded pipe. That fault you indicate is due to an obstruction in the high pressure line and may be due to the causes: clogged filter, moisture, bent pipe or closed or locked expansion valve. Friend any questions you comment here.