Component Test And Maintenance; Vacuum Pump; Pressure Sensor P1; Pressure Switch P2 - Bosch ACS 652 Repair Instruction

en 28 | ACS 652 | Component test and maintenance
12. Component test and main-
tenance
12.1

Vacuum pump

!
The vacuum pump oil must always be changed after
10 hours of operation.
Property
Operating voltage
Frequency
Vacuum pump oil filling capacity
Output
Max. vacuum
To check correct operation of the pump, carry out the
following steps:
1. Check the oil level in the vacuum pump.
i
The oil level should be in the middle of the
sight glass between the "full" and "empty" marks.
2. Attach pressure gage to intake connection.
3. Start vacuum generation
"
A vacuum of 0.05 mbar must be achieved.
12.2

Pressure sensor P1

1. Check whether a voltage of 24 Volt (DC) is present
between pin 1 (-) and pin 2 (+).
i
If no voltage is present, check the control PCB and
replace if necessary.
2. Check whether an output signal is present between
pin 1 (-) and pin 3 (+).
i
The output signal is between 0 V and 10 Volt, i.e.
1.0 Volt corresponds to 1.6 bar. If the pressure gage
shows 3 bar relative (4 bar absolute), the voltage
must be 2.5 Volt.
i
When replacing the pressure sensor, a special thread
sealant (e.g. Loctite 542) must be used.
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1 689 975 257 2019-05-15
12.3
i
The pressure switch is normally closed between
contacts 1 and 2, and open between contacts 1 and
4. The pressure switch opens at 14.5 bar.
To check the pressure switch, carry out the following
steps:
1. Close V1 - V4.
Value/range
2. Remove the red hose from the internal refrigerant
230 VAC ± 10 %
cylinder and connect the red service hose to the
50/60 Hz
internal refrigerant cylinder.
580 ml
3. Close both valves on the refrigerant cylinder.
170 l/min
4. Remove the blue hose from the internal refrigerant
0.05 mbar
cylinder and connect a pressure gage using a T-
piece.
5. Open V4
6. Open V1
7. Start the recovery function.
8. As soon as the pressure reaches 14.5 bar, recovery
must be ended, and the message
PRESSURE VALUE TOO HIGH
9. Drain the pressure into the internal refrigerant cylin-
der by opening the high pressure valve.
i
When replacing the pressure switch, a special weight
sealant must be used.
12.4
i
The expansion valve is a pressure control valve that
is set to a value between 2 and 2.3 bar and main-
tains a constant pressure before the oil separator.
!
The refrigerant cylinder must contain at least 4 kg of
refrigerant.
1. Connect the low pressure service hose to the con-
nection after the expansion valve using the adapter
supplied.
2. Close HP and LP valves.
3. Start the recycling function.
"
After around 10 minutes, the pressure value must be
between 2 and 2.3 bar.

Pressure switch P2

Expansion valve

is displayed.
Robert Bosch GmbH