SMART Fortwo 451 Series Introduction Into Service Manual page 80

Heater/AC operating unit
The heater/AC operating unit is located at the top
of the center console. The interior temperature
sensor is located under the temperature selector
wheel.
When the desired temperature is set, the request
for heating or cooling is transmitted to the driv-
etrain control unit via CAN C. This forwards the
output values requested by the heater/AC oper-
ating unit for the high-voltage PTC heater or the
requested rpm for the electric refrigerant
compressor to the corresponding components.
Heating:
Climate control takes place via the heater/AC
operating unit. This communicates with the
control unit in the high-voltage PTC heater via
CAN C. The control unit in the high-voltage PTC
heater activates the output stages in accordance
with the requested heat output.
Introduction of smart fortwo electric drive (3rd Generation) • Model Series 451
Cooling:
The drivetrain control unit communicates with the
control unit in the electrically driven high-
voltage refrigerant compressor via LIN. The
control unit of the electric refrigerant
compressor regulates the speed to the value set
by the heater/AC operating unit.
On vehicles with code (V03) Battery cooling
system, the electric motor is also regulated
depending on the cooling output request of the
high-voltage battery. These vehicles (for hot
countries) have an additional coolant/refrigerant
heat exchanger (chiller) in the refrigerant circuit
for cooling the high-voltage battery.
These vehicles are equipped with electrically
switchable expansion valves in order to allow the
interior and battery cooling systems to be acti-
vated independently.
Cooling of the high-voltage battery is controlled
by the battery management system control unit.
Climate control
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