G785

Coolant Circuit

AX4
V509
N632

G931

VX54

G789
JX1
G788

V508
G83

N687

8

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Radiator

The Heat Pump in the e-Golf
Key
AX4 High Voltage Battery Charger 1
G83 Engine Coolant Temperature Sensor on Radiator Outlet
G110 A/C Engine Coolant Temperature Sensor
G395 A/C Pressure/Temperature Sensor
G785 Temperature Sensor in Front of High Voltage Heater (PTC)
G787 Temperature Sensor after Heat Exchanger
G788 Temperature Sensor after Electro-Drive Drive Motor
G789 Temperature Sensor after Electric Drive Power and Control Electronics
G826 A/C Pressure/Temperature Sensor 2
G827 A/C Pressure/Temperature Sensor 3
G828 A/C Pressure/Temperature Sensor 4
G829 A/C Pressure/Temperature Sensor 5
G931 Temperature Sensor Before Charger
JX1 Electric Drive Power and Control Electronics
N632 Coolant Change-Over Valve 1
N636 Refrigerant Expansion Valve 1
N637 Refrigerant Expansion Valve 2
N638 Refrigerant Expansion Valve 3
N642 Refrigerant Cut-off Valve 4
N643 Refrigerant Cut-off Valve 5
N687 Radiator Bypass Switch-over Valve
N696 Refrigerant Cut-off Valve 1
V470 Electrical A/C Compressor
V508 Coolant Pump In Front of Electric Drive and Power Control Electronics
V509 Coolant Pump In Front if High Voltage Heater (PTC)
VX54 Three-phase Current Drive
Z115 High Voltage Heater (PTC)
Refrigerant Circuit
Coolant Circuit
The following terms are shortened in the remainder of this SSP:
• N636 Refrigerant Expansion Valve 1 to Expansion Valve 1 (EV1)
• N637 Refrigerant Expansion Valve 2 to Expansion Valve 2 (EV2)
• N638 Refrigerant Expansion Valve 3 to Expansion Valve 3 (EV3)
• N696 Refrigerant Cut-off Valve 1 to Cut-off Valve 1 (SV1)
• N642 Refrigerant Cut-off Valve 4 to Cut-off Valve 4 (SV4)
• N643 Refrigerant Cut-off Valve 5 to Cut-off Valve 5 (SV5)

9

Components
Electrical Air Conditioner Compressor
Location

Electrical A/C Compressor

The Electrical A/C Compressor V470 is bolted to the Threephase Current Drive VX54.

Design
The e-Golf with heat pump uses an electrical air conditioner
compressor with an internal scroll compressor design. It
is identical to the air conditioner compressor used in the
e-Golf without a heat pump.

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Function
The electrical A/C compressor draws in the gaseous
refrigerant at low pressure. It is compressed, the pressure
increases and the temperature of the refrigerant rises.
The electrical A/C compressor pushes the refrigerant to
the condenser as a hot gas. This compressor forms the
separating point between the low and high-pressure sides of
the refrigerant circuit.
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10

Components
Heat Condenser and Evaporator
Location of Heat Condenser/
Evaporator
The heat pump in the e-Golf has a heat condenser and
an evaporator. Both are located in the heater and air
conditioning unit.

Design of Heat Condenser

Evaporator

Heat Condenser
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The heat condenser is a serpentine-like pipe system with
fins. This creates a large heat exchange area with good
heat transfer. Airflow from the fan passes through the heat
condenser.

Heat Condenser

Heat Condenser Function
Condensation is the transition of matter from a gaseous to
a liquid state.

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The hot, gaseous refrigerant reaches the condenser. The
condenser pipes and fins absorb heat as cool outside air
flows across the condenser. As it cools, it condenses and
becomes a liquid. The cooled refrigerant is then guided
into the vehicle interior.

11

Components
Evaporator Design
The evaporator has a similar design to the heat condenser
and also has an internal flow of refrigerant. Air from
the heater and air conditioning unit flows through the
evaporator.

Evaporator

Evaporator Function
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The evaporator works as a condenser during heat pump
operation (“heating” function). This means that the air
flowing through the evaporator is heated.

The evaporator works as an evaporator in
“cooling” mode (function). This means that
the air flowing through the evaporator is
cooled.

Expansion Valves and Cut-off Valves
Locations of Expansion Valves/
Cut-off Valves
Three expansion valves and three cut-off valves are used in
the heat pump circuit:

N643

N642

N696
N636

• N636 Refrigerant Expansion Valve 1 (EV1)
• N637 Refrigerant Expansion Valve 2 (EV2)
• N638 Refrigerant Expansion Valve 3 (EV1)
• N696 Refrigerant Cut-off Valve 1 (AV1)
• N642 Refrigerant Cut-off Valve 4 (AV4)
• N643 Refrigerant Cut-off Valve 5 (AV5)

12

N637
N638

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Components
Design of Expansion Valves

Expansion Valve

The expansion valves have an identical design. A V-shaped
control edge in the ball valve enables on-demand, stepless
activation (0-100 percent).

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Expansion Valve Function
Refrigerant flows through the Expansion Valve
2 N637 from the evaporator in the direction
of the condenser in “heating” operating
mode (function). In “cooling” operating mode
(function), the refrigerant flows through the
expansion valve in the opposite direction.

The refrigerant can expand in the expansion valve, i.e. fill
a considerably larger space (volume enlargement). The
pressure then falls significantly. The liquid refrigerant
partially evaporates, causing the temperature to fall.

Design of cut-off valves
Cut-off Valve

The cut-off valves are ball valves that are either fully open or
fully closed.

Cut-off Valve Function

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The cut-off valves regulate the flow direction of refrigerant in
the refrigerant circuit.

The expansion valves and cut-off valves are connected to the Thermal Management Control Module J1024 via
the same LIN-Bus. Each compact valve connector has its own coded pin assignment.

13

Components
Condenser
Location
The condenser is located between the radiator fan and the
radiator.

Design
The condenser is a conventional air conditioner condenser.
Condenser
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Function
The condenser operates either as an evaporator or
a condenser according to the “cooling” or “heating”
operating mode (function).
It works as an evaporator in heat pump mode, i.e. in the
“heating” function. Evaporation refers to the transition from
a liquid to a gaseous state.
In the evaporator, the refrigerant, which is no longer under
pressure and is at ambient temperature, is completely
evaporated. The heat required for this is drawn from
the outside air that passes between the evaporator fins.
The pressure of the refrigerant remains constant and the
temperature rises slightly.

The evaporator functions as a condenser in
“cooling” operating mode (function).

14

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Components
Heat Exchanger for Heat Condenser
Location
The heat exchanger is located on a bracket mounted on
the bulkhead in the engine compartment. Most of the heat
pump components are mounted on it.

Design
The Heat Exchanger for Heat Condenser is just like
conventional oil-to-coolant plate heat exchangers.

Heat Exchanger for
Heat Condenser

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The coolant circuit is separate from the refrigerant circuit.
Heat is exchanged without direct contact between or mixing
of the fluids.

Key
Refrigerant circuit
Coolant circuit

Function
Connections for
Refrigerant

In the Heat Exchanger for Heat Condenser, the heat of the
coolant is transferred to the refrigerant and the refrigerant
evaporates.

Connections for
Coolant

The heat from electronic components such as the threephase current drive, the power and control electronics for
electric drive and the charging unit is used.

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15

Components
Reservoir
Reservoir

Location
The reservoir is upstream of the electrical air conditioner
compressor in the refrigerant flow direction.
The reservoir is located at the front right in the wheel
housing.

Design
It is identical to the reservoir in other vehicles with air
conditioning.

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Refrigerant Outlet
to Electrical Air
Conditioner
Compressor

Refrigerant
Inlet

Function
The reservoir is used in the refrigerant circuit as an
expansion and supply tank for the refrigerant. Since the
thermal loading of the evaporator and condenser and
the speed of the electrical air conditioner compressor will
vary during operation, different quantities of refrigerant
will also be pumped through the circuit. The reservoir
is incorporated into the circuit to compensate these
fluctuations.

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16

Components
Refrigerant Pressure and Temperature Sensors
Location
G395

A total of five refrigerant pressure and temperature sensors
are installed in the heat pump circuit.

G829

They are located on the assembly carrier:
G827

• G395 A/C Pressure/Temperature Sensor

G826

• G826 A/C Pressure/Temperature Sensor 2
• G827 A/C Pressure/Temperature Sensor 3
• G828 A/C Pressure/Temperature Sensor 4

G828

• G829 A/C Pressure/Temperature Sensor 5

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Function
The refrigerant pressure and temperature sensors measure
the pressure and the temperature of the refrigerant, convert
the readings into an electrical signal and send it to the heat
pump control module.
The following data is collected:
• Refrigerant pressure 0 to 36 bar
• Refrigerant temperature -40°C to +150°C
• Internal temperature sender -40°C to +140°C

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Failure Effects

The refrigerant pressure and temperature
sensors can only be replaced after the
refrigerant has been extracted.

If one or more sensors fail, the refrigerant pressure and the
refrigerant temperature are determined using a map. The
heating up phase for the vehicle interior is increased and an
entry is made in the event memory.

17

Components
Coolant Change-Over Valve 1 N632
Location
The Coolant Change-Over Valve 1 is located in the coolant
circuit.

Design
The Coolant Change-Over Valve 1 is a 3/2-way valve.

Z115

AX4
N632

JX1

Function
This valve is used to switch between the large coolant circuit
and the small coolant circuit with the high voltage heater
(PTC). When not powered, it is constantly open and only
the large coolant circuit is active. The heat-up phase of the
vehicle interior takes longer.

s532_092

To High-voltage
Heater (PTC) Z115

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