A vacuum pump is a piece of equipment that will allow you to pull a vacuum on your car's a/c system. They fairly simple and inexpensive to operate. First, turn off your car's air conditioner and shut the engine down. You don't hook the vacuum pump directly to the A/C system. You to first hook up a refrigerant gauge manifold set to the low pressure port on the system. (Generally, this is the blue hose that is attached to the gauges.) On your gauge set there is a port in the middle. This is where you connect the vacuum pump. Using a gauge manifold set allows to shut down the vacuum pump without