STUD 2751185 - Caterpillar

Table 1
Boiling Point of Water Under Vacuum
Temperature of Work Area (°C (°F)) Vacuum That Is Required In Order To Boil Water In An Air Conditioning System (m bar (Hg))
38 °C (100 °F) 95 kPa (28 in Hg)
32 °C (89.6000 °F) 96.5 kPa (28.50 in Hg)
27 °C (81 °F) 97.5 kPa (28.80 in Hg)
21 °C (70 °F) 98.8 kPa (29.20 in Hg) Note: After the leak test is completed, the system must be evacuated for a minimum of 30 minutes. In order to correctly evacuate the system, the vacuum gauge must be less than three inches away from the system port. If the gauge is more than three inches away from the system port, pull a vacuum and allow the system to equalize for ten minutes. This will ensure an accurate gauge reading.
All refrigerant must be recovered before the evacuating procedure is started. Never discharge the refrigerant through the vacuum pump. Never discharge the refrigerant into the atmosphere. Always use the Refrigerant Identifier tool in order to ensure that contamination of the system does not occur.
Illustration 1 g00452649
(1) Low pressure valve
(2) High pressure valve
(3) Charging hose
(4) Compressor block fitting (discharge)
(5) Compressor block fitting (suction)
(6) Service valve (discharge)
(7) Service valve (suction)
(8) Vented exhaust valve
(9) Line from condenser
(10) Line from evaporator
After the refrigerant is recovered from the system, make sure that the low pressure valve (1) and the high pressure valve (2) are closed. Disconnect the charging hose (3) of the manifold gauge set from the refrigerant service unit.
Check the oil level in the vacuum pump. Refer to the Testing and Adjusting, "Refrigerant Compressor Oil - Check" for the correct procedure. Add oil if oil is needed. If contamination of the system is indicated, change the oil.
Connect the electrical plug from the vacuum pump to an approved electrical outlet.
Connect the charging hose (3) to the inlet fitting on the vacuum pump. Refer to Illustration 1.
Open low pressure valve (1) and open high pressure valve (2) on the manifold gauge set completely. Turn the valves counterclockwise.
In order to start the pump motor, turn the power switch to the ON position.
In order to open the vented exhaust valve (8), turn the valve counterclockwise.Note: The vented exhaust valve (8) must be closed until the vacuum pump has started.
Operate the vacuum pump until the low pressure gauge indicates a pressure that is between 95 kPa (28 in hg) and 98 kPa (29 in hg). After the vacuum in the system reaches a value that is between 95 kPa (28 in hg) and 98 kPa (29 in hg), close the vented exhaust valve (8). Operate the vacuum pump for a minimum of 90 minutes after the vented exhaust valve is closed. Use a 113 L/min (4 cfm) pump. Make allowances for pumps that are smaller than 113 L/min (4 cfm) cfm.Note: 95 kPa (28 in hg) to 98 kPa (29 in hg) is the required specification at sea level. For every 305 m (1000 ft) above sea level, decrease the required specification by