Electrical System Operation; Power Board And Power Supply Operation; Power Board Connector Assignments - Bosch ACS 553 Service Manual

Electrical

ELECTRICAL SYSTEM OPERATION

The electrical system provides the various
voltage levels required for the machine to
operate effectively. The power board, power
supply, and control board work together to
condition the input voltage by removing voltage
spikes and noise, transforming the input voltage
to 12 VDC (power supply) for operating relays
and voltage regulators (power board), to power
the unit cooling fan, engage the compressor
and vacuum pump when required. Inputs from
the sensors and transducers are processed
(control board), to ultimately power the manifold
solenoids (power board) for recovering and
recharging vehicle A/C systems.

Power Board and Power Supply Operation

The Power Board is shown in Figure 3-1. The
Power Supply is shown in Figure 3-2. Refer to
these figures as needed.

Power Board Connector Assignments

See Figure 3-1, Power Board for connector
locations:
J1: Control Board J1
P1: Power Supply J2
P2: Control Board P19
P3: AC Input
P4: Power Supply J1
P6: Vacuum Pump, Compressor
P7: High-Pressure Switch
P4
P3
P6
K3
K4
P5
Figure 3-1. Power Board
1 689 975 295 2021-04-13
P8
J1
P1
P7
P2
56
ACS 553, ACS 563 Service Manual
P8: Solenoids S4-1, S4-2, S5-1, S5-2, S6, S7,
S8, S9, S11, S13, S14 and Fan.
The Power Board (PB) receives AC voltage at
PBP3 from the power switch to PBP3 pins:
• Pin 1 – Unit ground
• Pin 2 – AC low
• Pin 3 – AC high
The input voltage is immediately applied to
the Power Supply (PS) through PBP4 and
the interconnecting cable to PSJ1. The output
of the power supply is 12 V ± 0.1 VDC. This
is the main system control voltage and used
throughout the unit for its various functions
through PSJ2 to PBP1 and Control Board
(CB) receives 12 VDC from power board PBP2
through an interconnecting cable to CBP19
(See Control Board Functions). Relay K3 is
used to couple the 12 V output from the power
supply to the power board through PBP1.
Input AC voltage within the power board is also
routed to relays K3 and K4. Relay functions are:
• K3 – Compressor
• K4 – Vacuum Pump
Power for the vacuum pump, and compressor is
routed to those units through PBP5 and PBP6
and wiring harnesses.
J1
Figure 3-2. 12 VDC Power Supply
1
J2
6
V Adj.
Robert Bosch GmbH