306
REVO-E Heat pump 3 Assemblies and components
Double radial blowers
The six double radial blowers are driven by EC motors.
The blowers move recirculated / fresh air through the heat
inner exchanger and blow it at the right temperature
(depending on the mode) into the air ducts of the vehicle.
Speed controls are continuous (PWM); e.g. speed is
reduced when the desired passenger compartment
temperature has been reached. This reduces energy
needs and helps to stabilize the passenger cabin temper-
ature.
Frequency converter
This component is supplied via the 600V DC electrical
system of the vehicle and provides 400V AC for the three-
phase AC motor of the compressor. Depending on system
requirements, the compressor speed is set between
10Hz-50Hz.
The frequency converter is placed onto an adapter plate
(Fig. 803), which makes it easy to remove / install.
4-Way reversing valve
Depending on the position, the 4-way reversing valve acti-
vates the air conditioning mode or the heat pump mode.
In zero position, the air conditioning mode is active.
Solenoid valve hot gas deicing REVO-E HP +
The hot gas deicing solenoid valve is installed on the
11123865_ ONLY. It is activated to defrost the outer heat
exchanger with hot gas from the refrigerant circuit.
Sensors
Suction pressure
The suction pressure sensor determines the pressure
level in the permanent low-pressure area. The system
attempts to manage the suction pressure between 3.0 bar
and 3.7 bar (absolute).
Central parameters for:
– climate/ heat pump control
– recognizing icing
– recognizing low pressure
High pressure
The high pressure sensor determines the pressure level in
the permanent high-pressure area.
In heat pump mode, the target pressure is approx. 12 bar
depending on the ambient temperature.
Passenger compartment temperature
This sensor measures the air temperature of the
passenger cabin around the intake area of the recircu-
lating air (Fig. 908).
Air duct temperature (blow-out temperature)
This sensor measures the air intake temperature of the
air-conditioning system at the first double radial blower,
front right (Fig. 908).
Monitoring the temperature of the e-motor of the
compressor
A PTC element monitors the temperature of the
compressor e-motor. The frequency converter evaluates
the signal without directly influencing the air-conditioning
control.
R25 ≤ 300 Ω
If the e-motor overheats, the frequency converter stops
the compressor immediately (safety function).
Air valves
Regulate the intake of fresh air or use of recirculated air
from the passenger cabin. The BEA body sends the posi-
tional signals “open / closed” via CAN to the SC620 in all
operating modes (except for Gas Charging mode). If both
signals are active, the valves will move to the Recircu-
lating position. Intermediate positions (air mixing) are not
provided in this vehicle.
SC620
This control unit is used as the control device in the Volvo
7900 Electro system (display / keyboard inactive).
HVAC demands are only managed by the BEA body, the
SC620 works as a “slave system” and controls the func-
tions of the ADA.
Two LEDs become active when the system is turned on
(permanent & blinking).
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