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Air conditioning systems with refrigerant R1234yf - General information - Edition 07.2017
1.2.17
High-pressure safety valve
The high pressure safety valve is fitted to the air conditioner com‐
pressor or the receiver.
The valve opens at a pressure of approx. 38 bar (overpressure)
and closes again when the pressure has dropped (to approx. 35
bar).
Not all the refrigerant is lost from the system.
Note
♦ Depending on the version, a transparent plastic washer -B-
may be attached to the high pressure safety valve -A- which
breaks off as soon as the valve is actuated.
♦ Depending on the version of high pressure safety valve -A-, a
cover -C- may also be pushed onto the high pressure safety
valve -A-. Should the pressure in the refrigerant circuit actually
rise above the opening pressure of the high pressure safety
valve -A- and cause the valve to open, refrigerant will not es‐
cape in one direction but scatter through the openings -D-
beneath the cover -C- instead.
♦ If a high-pressure safety valve -A- needs to be renewed, the
specified torque for the new valve (depending on the manu‐
facturer and the version of the air conditioner compressor)
must be observed when installing. Air conditioner compres‐
sors manufactured by “Denso”, “Sanden” and “Valeo” are
equipped with an O-ring seal (currently valid torque settings
are: 10 Nm for “Denso” and “Zexel/Valeo” air conditioner com‐
pressors, and 15 Nm for “Sanden” air conditioner compres‐
sors). Air conditioner compressors manufactured by “Delphi”
are fitted with an oil seal (currently valid torque setting: 15 Nm).
lk
♦ Renewing seals (oil seals or O-rings) ⇒ Electronic parts cata‐
logue .
♦ If a seal (oil seal or O-ring) fitted to the high-pressure safety
valve is not available as a replacement part, the removed old
part can be reused (as an exception to the general rule of using
new seals only). The old seal, however, must always be
checked for damage prior to installation. If any damage or de‐
formation is detected on the old seal, it must be renewed with
a commercially available new part ⇒ Electronic parts cata‐
logue .
♦ After filling the refrigerant circuit, check the installed high-
pressure safety valve for leaks using e.g. an electronic leak
detector.
1. Refrigerant circuit
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