How do you pump down a heat pump unit?

The process of pumping down a heat pump is quite simple. First you should switch the unit into air conditioning and put your compound gauge on the suction line. Make sure the unit is running. Then valve off the discharge line and watch your gauge pressure. When it pulls itself down into a vacuum the heat pump is pumped down within itself. Make sure to valve off the suction line to make sure no refrigerant is released back into the air handling unit. You should now be able to lay some wet rags on the valves to protect them if you desire to sweat the unit away from the line set.