Unit Evacuation

Turn on the vacuum pump. Open the gas ballast valve located on top of the pump housing behind the handle (the valve is fully open at two turns counterclockwise). Evacuate the system to 500 microns to achieve a final equilibrium pressure of 2000 microns or less. The final equilibrium pressure is determined with the Thermo King Evacuation Station using the following procedure (called a pressure rise test):

1. Evacuate the system using the evacuation station until the vacuum level reaches 1000 microns. Then close the gas ballast valve.

2. Continue evacuation to 500 microns or until vacuum stabilizes at its lowest level. Contamination may delay reaching the lowest level for a period of several hours or more.

3. Close valve V1 to isolate the vacuum pump from the system.

4. Observe the vacuum level on the micron meter.

When the meter has stabilized, the value indicated on the micron meter is the equilibrium pressure. This reading must be 2000 microns or less.

If the vacuum level appears to stall above 500 microns, back seat the discharge service valve and observe the micron meter.

• A drop in pressure indicates that the compressor oil is out-gassing and further evacuation is necessary.

• An increase in pressure indicates that a leak exists or there is moisture in the system. Perform a pressure rise test and evaluate.

Close valve V1 when the desired vacuum level has been reached.

Wait five minutes and read the micron meter.

• A system that is leak free and dry will remain below 2000 microns for five minutes.

• A system that rises above 2000 microns but stabilizes below atmospheric pressure is probably contaminated with moisture or has refrigerant out-gassing from the compressor oil. Additional evacuation is required.

• A system that continues to rise without stabilizing has a leak and must be repaired.

If the vacuum level remained below 2000 microns for five minutes, the unit is ready to charge. Refer to (Charging System with Refrigerant).