TM 5-3805-292-23
0093
EVACUATION CONTINUED
1. Ensure manifold gauge set (Figure 2, Item 2) and valves (Figure 2, Items 3 and 7) are closed.
2. Disconnect charging hose (Figure 2, Item 4) from recovery station inlet (Figure 2, Item 5) on refrigerant service
unit.
3. Check oil level in vacuum pump. Add oil as necessary. Refer to vacuum pump OEM manual for correct
procedure.
4. Connect charging hose (Figure 2, Item 4) to inlet (Figure 2, Item 6) on vacuum pump.
5. Open both manifold gauge set (Figure 2, Item 2) and valves (Figure 2, Items 3 and 7) completely. Turn valves
counterclockwise to open.
6. Evacuate A/C system. Refer to vacuum pump OEM manual for operation instructions.
N OT E
At high elevations, less vacuum is required. 28 to 29 inHg (95 to 98 kPa) is the required
specification at sea level. For every 1,000 ft (305 m) above sea level, decrease the
required specification by 1 inHg (3 kPa).
AMBIENT
VACUUM REQUIRED TO BOIL WATER
TEMPERATURE F (C)
IN A/C SYSTEM INHG (KPA)
100F (38C)
28 inHg (95 kPa)
90F (32C)
28.5 inHg (96.5 kPa)
81F (27C)
28.8 inHg (97.5 kPa)
70F (21C)
29.2 inHg (98.8 kPa)
7. Operate vacuum pump until low pressure gauge (Figure 2, Item 1) indicates a vacuum between 28 and 29
inHg (95 and 98 kPa).
8. After vacuum in A/C system reads between 28 and 29 inHg (95 and 98 kPa), operate vacuum pump for a min-
imum of 90 minutes.
N OT E
Evacuating procedures remove air and moisture from the system. Do not use the vacuum
pump primarily to indicate a system leak.
9. If specific vacuum cannot be reached, A/C system may have a leak. Repair all leaks and repeat steps 1
through 8.
0093-4
