Internal Heat Exchanger; The Airflow Limiter - Volkswagen Golf 2014 Service Training

Heating and air conditioning

Internal heat exchanger

A new feature in the Golf is the so-called "Internal
heat exchanger" (IWT), which was used for the first
time in the Volkswagen Touareg. This is a refrigerant
line that forms a "pipe-in-pipe system". This
refrigerant line features a low-pressure line which is
guided through a separate space in the high-pressure
line. The refrigerant flows through the outer line to the
expansion valve (high pressure), and flows back from
the expansion valve through the inner line towards
the air conditioner compressor (low pressure).
This design increases the efficiency of the system and
contributes to reducing the fuel consumption.

The airflow limiter

On vehicles with a heater and air conditioning
system, the same fresh air blower V2 and control unit
J126 is installed as in vehicles with an air conditioning
system. However, in this case there is no evaporator
to reduce the air flow.
An air flow limiter has therefore been installed in the
heater unit in these vehicles. This guarantees that the
heater and blower power operates optimally.
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High pressure
Low pressure
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Air flow limiter