How to Use a Air Conditioning Vacuum Pump on Your Car

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 losing the vacuum you have just created. If you just hooked the A/C vacuum pump straight to your air conditioner, you would lose the vacuum as soon as you unscrewed the connector from the port. With the gauges, you can measure the vacuum and add refrigerant to the system.

Now, hook up your refrigerant gauge manifold set and screw on your A/C vacuum pump to the center port. When the vacuum reaches 27 Hg, let the pump run for another 30 minutes. Now, close the valve for the center port and turn off the vacuum pump. Leave the gauges connected to the A/C system and go take a 20 to 30 minute break. When you return, pick up the manifold gauges and verify there is still a vacuum. If in that time you have lost some of the vacuum, then there is a leak somewhere. If the gauge still reads 27 Hg, you are ready to add refrigerant.

After you connect the center port of your refrigerant manifold gauges to a can refrigerant, start the car's engine and turn on the air conditioner. Now slowly open the low pressure manifold and let the freon flow into the system.