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Home >> Pontiac >> 1991 >> Grand AM L4-151 2.5L >> Repair and Diagnosis >> Heating and Air Conditioning >> Service and Repair >> Vacuum Pump Check
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Vacuum Pump Check

VACUUM PUMP CHECK
Before connecting a vacuum pump to the A/C system, connect the pump to the low-pressure gage to determine the vacuum pump's capability. If the vacuum pump is unable to reach at least 94.5-97.9 kPa (28"-29" Hg.)vacuum, check the system for leaks. If no leaks are found, the vacuum pump may require repair.

This specification can be reached only at or near sea level. For each 304.8 m (1,000 feet) above sea level, lower the specification by 3.37 kPa (1" Hg.). For example, at 1,524 m (5,000 ft.) elevation, only 77.67-84. 42 kPa (23"-24" Hg.) vacuum is required.

NOTE: When a vacuum pump is used in EITHER of the two methods, it must be able to reach these specifications (94.5-97.9 kPa, 28"-29" Hg.), or as adjusted for altitude.
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