Using a high-quality electric vacuum pump along with a manifold set is another good method for evacuating the AC system. This method of pulling a vacuum on an AC system requires a little bit more technical skill than using the recovery/recharging machine because it is important to have all of the valves in the correct position while the process is going on as well as when it is time to stop the vacuum process. Follow these steps to vacuum a system with an electric vacuum pump.
A quality electric vacuum pump is needed to pull a good vacuum on the AC system each time it has been opened for service or each time that the refrigerant has leaked out. Pulling a vacuum on the AC system removes air and moisture prior to adding the refrigerant back into the
Evacuating the AC System with an Electric Vacuum Pump
1. Connect the blue hose of the manifold set to the low side service port and turn the blue knob clockwise to depress the check valve.
The blue hose on the manifold set is for connecting to the low side service port. The low side service port is a 13-mm quick-connect
2. Connect the red hose of the manifold set to the high side service port and turn the red knob clockwise to depress the check valve.
The red hose on the manifold set is for connecting to the high side service port. The high side service port is a 16-mm quick-connect
3. Connect the yellow hose of the manifold set to the port on the vacuum pump by threading the connection in a clockwise rotation.
The yellow hose from the manifold set connects to the electric vacuum pump threaded connector. This connection should be tightened to a snug level using a firm
4. Open the valves at the manifold by turning the blue and red knobs counterclockwise. This lets the blue and red hoses be open to the yellow hose that is connected to the vacuum pump.
The blue valve on the manifold set should be turned counterclockwise, which opens the valve to allow the yellow hose to pull a vacuum through the blue
5. Turn the vacuum pump on and make sure the check valve is set to open to allow the pump to pull a vacuum on the service port.
6. Watch the gauges on the manifold set drop. The red gauge will drop down to 0 psi and the blue gauge will drop to below 0 psi, which will be in the vacuum part of the gauge that is in inches of mercury. The blue gauge should reach 20 inches of mercury within 10 minutes of operation.
The low side gauge should drop into the vacuum portion of the scale within few a minutes of running the vacuum
7. This process should pull the low side gauge to 29 inches of mercury, which will remove any moisture from the AC system. The vacuum time should be at least 30 minutes if the system has been open to the atmosphere.
The low side gauge should read a deep vacuum and the high side gauge should be pulled to the lowest setting after the vacuum pump has run for at least 30
8. To stop the vacuum process, turn the blue and the red knobs on the manifold set clockwise to block the vacuum process. The vacuum pump can now be turned off and the yellow hose can be removed. The vacuum should stay constant on the blue gauge, which shows that the system does not have any leaks. The system is now ready to be charged with refrigerant.
The manifold valves should be turned clockwise, which closes the valve and traps the vacuum in the AC system. The vacuum can be turned off and the yellow hose can be removed from the vacuum
