If the central air contour has been opened and atmospheric air has got to it, it is necessary for pumping out, using the vacuum pump. If the system has been opened within several days, it is necessary to replace the receiver / a dryer.
Start the pump and open both valves. Leave the pump to work during 15 mines, then close valves and switch off the pump. The manometre of low pressure should show more than 700 мм.рт.ст. And this pressure should remain at the closed valves.
If low pressure does not reach more than 700 мм.рт.ст. During 15 mines, in a central air contour there is a leak.
If leaks in a central air is not available, open valves and continue pumping out during the subsequent 15 mines then close both valves and stop the pump.