Vacuum Pump Troubleshooting - Bosch ACS 753 Repair Instructions

ACS 753, ACS 763, ACS 863 Service Manual

Vacuum Pump Troubleshooting

1. Check gauges for vacuum.
2. If pressure is over 0.7 bar (10 psi), recover
hoses.
3. If unit won't maintain vacuum, check
high- and low-side charge solenoids,
hoses, couplers, gauges, and other related
components, for leakage.
4. If there is no pressure on the gauges and
the 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 control board.
5. If the compressor is not running or appears
to be running poorly, refer to Vacuum Pump
Does Not Run.
Figure 2-2. Vacuum Pump Assembly
Robert Bosch GmbH
Diagnostics and Testing
Vacuum Pump Does Not Run
1. Check for proper power source, circuit
breaker, and electrical connectors for
damage or corrosion. Replace or repair as
required.
2. Connect the unit power cable directly to the
power source. Do not use an extension cord.
3. Check for 230 V at the vacuum pump
connector, pins 2 and 3.
• If voltage is present, replace vacuum
pump assembly.
• If voltage is not present, continue to next
step.
NOTE: When checking voltage to the vacuum
pump it is normal to read low voltage at the
connector when it's disconnected and the power
to the vacuum pump is off.
4. Check for 230 V from the power board on
connector P6 pins 3 and 4.
• If voltage is present, check wiring between
the power board and the vacuum pump.
Repair as needed.
5. Use the output test and verify fan operation.
• If the fan is not functioning, check/verify
wiring, switches, and circuit breaker.
• If the fan is functioning, replace the power
board.
• If voltage is not present, replace the
power board.
NOTE: If fan works, power is present at the
power board. The fan, vacuum pump, and
compressor use the same power source.
6. Perform functional check.
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SP00D00609 2018-03-26