Bosch ACS 653 Repair Instruction page 106

Plumbing and Mechanical
ACS 653, ACS 663 Service Manual
VACUUM LEAK TEST PROCESS
HS and LS inlet solenoids are activated to equalize high and low sides of system being serviced. Unit checks low-side
transducer for rise in vacuum. If the unit sees a pressure rise within 5 minutes time, the vacuum leak test will fail..
Figure 4-14. Vacuum Leak Test
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SP00D00624 2021-04-08 Robert Bosch GmbH