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7 Clearing refrigerant circuit of contam‐
inants
7.1 Blowing through refrigerant circuit with
compressed air and nitrogen
• Use compressed air to force moisture and other contaminants
out of the refrigerant circuit and use nitrogen to force moisture
out of the refrigerant circuit.
• The method of blowing through the refrigerant circuit with
compressed air and nitrogen often requires a lot more work
than purging with refrigerant R134a. When purging with re‐
frigerant R134a, cleaning of the components is considerably
better. It is therefore always best to purge the system in the
event of complaints (the method of blowing through should
only be selected for certain complaints and for individual com‐
ponents).
Only individual components are to be blown through if:
♦ There is no way of purging the refrigerant circuit with refriger‐
ant R134a.
♦ If there is dirt or contamination in individual components of the
refrigerant circuit.
♦ If during evacuation of a leak-tight refrigerant circuit the vac‐
uum display is not constant on gauge (moisture in the refrig‐
erant circuit, which generates vapour pressure).
♦ If the refrigerant circuit has been left open for longer than nor‐
mally required for repairs (e.g. following an accident)
♦ Pressure and temperature measurements in the circuit indi‐
cate that there is moisture in the refrigerant circuit.
♦ The vehicle-specific repair manual ⇒ Heating, air conditioning
deems it necessary after replacement of certain components.
Note
♦
Blowing through the refrigerant circuit with compressed air and
nitrogen will not achieve the same degree of cleanliness as
purging with refrigerant R134a. When purging with refrigerant
R134a, the refrigerant oil is shifted and cleaning of the com‐
ponents is better ⇒ page 67 .
♦
When blowing through, a maximum working pressure of 15 bar
must not be exceeded (if necessary, use pressure limiter for
compressed air as well).
WARNING
♦ Nitrogen can escape from the bottle in an uncontrolled
way.
♦ Work only with pressure regulator for nitrogen bottles
(max. working pressure 15 bar).
♦ The gas mixture escaping from the components must be
collected with appropriate extraction equipment.
Amarok 2011 ➤ , Beetle 2012 ➤ , Bora 1999 ➤ , CC 2010 ➤ , CC 2012 ➤ , ...
Air conditioning system with refrigerant R134a - Edition 10.2014
7. Clearing refrigerant circuit of contaminants 65
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