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Air conditioning systems with refrigerant R1234yf - General information - Edition 07.2017
♦ The high pressure sender shown is installed e.g. in the Golf 7
and Audi A3 ⇒ Heating, air conditioning; Rep. gr. 87 ; Re‐
frigerant circuit (vehicle-specific workshop manual).
♦ One version of pressure sender generates a square-wave sig‐
nal when voltage is applied. This signal changes with the
pressure in the system. The other version of pressure sender
exchanges information with the corresponding control unit via
data bus (e.g. via the “LIN bus”) when voltage is applied ⇒ Cur‐
rent flow diagrams, Electrical fault finding and Fitting locations
and ⇒ Vehicle diagnostic tester in “Guided Fault Finding”
mode - air conditioning system. Therefore, pay attention to the
correct version of pressure sender.
♦ The pressure senders come in different versions. Depending
on the version, they can currently only be distinguished exter‐
nally by the part number, which is why attention should be paid
during renewal to their correct allocation (part number ⇒ Elec‐
tronic parts catalogue ). Reason: These senders emit different
lk
signals, and the relevant control units can only evaluate the
signal to which they have been matched ⇒ Vehicle diagnostic
tester in “Guided Fault Finding” mode - air conditioning system
and ⇒ Heating, air conditioning; Rep. gr. 87 ; Refrigerant cir‐
cuit (vehicle-specific workshop manual).
♦ One version of pressure sender only transmits the measured
value for the pressure in the refrigerant circuit to the connected
control unit. The other version transmits the measured value
for the pressure in the refrigerant circuit and the measured
temperature to the connected control unit, which is why atten‐
tion should be paid to the correct version ⇒ Electronic parts
catalogue .
♦ With this signal, the downstream control units calculate the
pressure in the refrigerant circuit and actuate the radiator fans
and engine, the air conditioning system magnetic clutch - N25-
accordingly or manipulate actuation of the air conditioner com‐
pressor regulating valve - N280- ⇒ Vehicle diagnostic tester in
“Guided Fault Finding” mode - air conditioning system and ⇒
Heating, air conditioning; Rep. gr. 87 ; Refrigerant circuit (ve‐
hicle-specific workshop manual).
1.2.22
Refrigerant pressure and temperature
sender
CAUTION
Risk of freezing injury caused by escaping pressurised refrig‐
erant.
There is a risk of injury to the skin and parts of the body due to
freezing.
– Wear protective gloves.
– Wear protective goggles.
– Extract refrigerant and open the refrigerant circuit immedi‐
ately afterwards.
– If more than 10 minutes have passed since the refrigerant
was extracted, repeat the extraction process before opening
the refrigerant circuit. Pressure could build up in the refrig‐
erant circuit from continued evaporation.
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Rep. gr.87 - Air conditioning system
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