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Air conditioning systems with refrigerant R1234yf - General information - Edition 07.2017
Note
♦ The vacuum at the end of the evacuating process (running of
vacuum pump of air conditioner service station ) must be less
than 5 mbar absolute pressure. Should pressure during the
evacuating process in the refrigerant circuit not be less than
5 mbar, this could have various causes. For example, leaks in
the refrigerant circuit or in the connection to the air conditioner
service station , the time for the evacuating process is set too
short, the vacuum pump of the air conditionerlkservice station
does not generate the necessary vacuum or the vacuum sen‐
sor of the air conditioner service station is not calibrated prop‐
erly ⇒ Operating instructions air conditioner service station .
♦ An absolute pressure of 5 mbar equates to a vacuum of
975 mbar at an ambient pressure e.g. of 980 mbar.
♦ At the end of the vacuum/pressure increase check, pressure
in the refrigerant circuit should not be greater than 20 mbar
absolute. Should the pressure in the refrigerant circuit be
greater than 20 mbar during the vacuum/pressure increase
check, the vacuum pump is switched on and the process is
repeated from the beginning ⇒ Operating instructions air con‐
ditioner service station . Should pressure in the refrigerant
circuit still not be less than 20 mbar even after the process has
been repeated twice, this could have various causes. For ex‐
ample, there could be leaks in the refrigerant circuit, a leak in
the connection from the refrigerant circuit to the air conditioner
service station or in the air conditioner service station itself,
the time set for the evacuating process is too short and the
time set for the vacuum/pressure increase check is too long.
♦ If there is reason to suspect a leak in the refrigerant circuit,
switch off the air conditioner service station if necessary and
allow it to stand for as long as possible (e.g. for at least 1 hour
to check the leak-tightness of the refrigerant circuit) ⇒ Oper‐
ating instructions air conditioner service station .
♦ Depending on the version of air conditioner service station ,
the pressure in the refrigerant circuit is displayed directly.
However, there is also a chance that the current pressure is
only displayed while the vacuum pump is running ⇒ Operating
instructions air conditioner service station . In the event of an
air conditioner service station only displaying the ambient
pressure, the display of the pressure in the refrigerant circuit
will depend on the ambient pressure during activation (ambi‐
ent pressure at 980 mbar, a vacuum of 975 mbar equates to
a residual pressure of 5 mbar absolute).
♦ If the refrigerant circuit was opened, small quantities of mois‐
ture may have entered the refrigerant circuit. In this case, the
refrigerant circuit is to be evacuated for at least 30 minutes
(pressure in the refrigerant circuit before charging must be less
than 20 mbar).
♦ If the refrigerant was extracted (to check the fill volume) and
the refrigerant circuit was only evacuated so that it could be
recharged (the refrigerant circuit was not opened and is leak-
tight), it is sufficient to evacuate the refrigerant circuit for 5
minutes and to set no time or only a short time (e.g. 1 minute)
for the vacuum/pressure increase check (no air or moisture
entered the refrigerant circuit).
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Rep. gr.87 - Air conditioning system
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