Fails Leak Test - Bosch ACS 553 Service Manual

Diagnostics and Testing
Vacuum Pump Not Running
1. Check gauges for vacuum.
2. If pressure is over 690 mBar (10 psi), clear
hoses. If unit won't maintain vacuum, check
the following for leakage:
• Tank Liquid solenoid (S7).
• Hose couplers.
• Hoses.
• Gauge tubing.
• Suction side vacuum hoses and connec-
tions.
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.
1 689 975 295 2021-04-13
ACS 553, ACS 563 Service Manual

Fails Leak Test

NOTE: To ensure an accurate leak test, it
is imperative that a thorough recovery and
evacuation of the system be performed. During
the recovery process, cold spots can develop
in an automotive system. Pockets of refrigerant
in desiccant and in system oil will continue
to vaporize as the A/C system temperature
equalizes toward ambient. As this occurs, A/C
system pressure will increase, which may be
interpreted by the unit as a leak. This will vary
somewhat with ambient temperature conditions.
1. Verify the service hoses are properly
attached to the unit (valves open) without
any restrictions.
2. If vacuum can not be maintained, using
Service Leak Check in the service menu,
pressurize the unit and use a leak detector
to check all hoses, fittings, and components
for leaks. Repair as needed.
3. Check the oil inject (S14), tank Liquid (S7)
and vacuum (S9) solenoids for bleed-
through. Repair as needed.
NOTE: A leaking tank liquid solenoid (S7) may
be identified by an internal pressure rise above
zero. A leaking vacuum (S9) or oil inject (S14)
solenoid would not normally rise above zero.
4. Verify the low-side pressure transducer is
functioning properly. Enter service menu
and verify low-side inlet transducer reading.
• Compare the low-side transducer reading
shown in the service menu with the
reading on the low-side panel gauge. The
readings should match, assuming the
low-side panel gauge is accurate.
• If the low-side inlet transducer is reading
pressure while the system is in a vacuum,
replace the transducer. Verify the
replacement transducer reads zero at
atmosphere by plugging it into the wiring
harness prior to installation.
• If replacing the transducer doesn't correct
the reading, replace control board.
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Robert Bosch GmbH