Will Not Evacuate (Vacuum) - Bosch ACS 753 Repair Instructions

ACS 753, ACS 763, ACS 863 Service Manual

Will Not Evacuate (Vacuum)

NOTE: The vacuum pump should be running
during this test. If the pump does not run,
refer to Vacuum Pump Troubleshooting in the
Vacuum Pump section of this manual.
1. Verify the service hoses are properly
attached to the unit (valves open) without
any restrictions.
2. Make sure the two plastic vacuum lines
are snug at both ends and not obstructed.
Check the pneumatic fittings for leaks.
3. Check for proper vacuum oil level in the
vacuum pump sight glass (oil level should
be in the center of the sight glass while the
pump is running). Replace vacuum pump
oil if necessary.
4. Check for suction at the intake of the pump.
If there is none, replace the pump.
5. Verify the vacuum solenoid (S9) is receiving
power and that the low-side (S4) and high-
side (S5) inlet solenoids are open.
• If not receiving power, check continuity
of the wiring between the solenoids and
power board. Repair as needed.
• If the wiring is correct and no power is
being applied to the solenoid, replace the
power board.
6. Check the PAG (S2), POE (S14) and dye
(S15) solenoids for bleed-through and
proper operation. This can be done by
checking for suction at the oil/dye inject tube
in the oil/dye inject bottle. Remove the oil/
dye inject bottle during the vacuum process
and check for suction at oil/dye inject tube
or watch for oil/dye movement in the tube
towards the manifold. Repair as needed.
7. Verify the low-side pressure transducer is
functioning properly.
Robert Bosch GmbH
Diagnostics and Testing
Vacuum Pump Not Running
1. Check gauges for vacuum.
2. If pressure is over 690 mBar (10 psi), recover
hoses. If unit won't maintain vacuum, check
the following for leakage:
• High-side charge solenoid (S6) and low-
side charge solenoid (S7).
• Hose couplers.
• Hoses.
• Gauge tubing.
• Injection manifold.
• S u c t i o n s i d e v a c u u m h o s e s a n d
connections.
3. If there is no pressure on gauges and
display says Pressure Exists, enter the
service menu and verify low-side inlet
transducer reading. If it is reading pressure
where none exists, replace transducer. If
replacing the transducer doesn't correct the
reading, replace the power board.
4. Refer to Vacuum Pump Does Not Run in
electrical troubleshooting.
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SP00D00609 2018-03-26