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repeated as described; this operation facilitates the removal of trapped and/or frozen humidity during the
evacuation process
4.3
Evacuating a circuit "contaminated" with refrigerant
The first step is to remove the refrigerant from the circuit using a specific machine with a dry compressor
for recovering the refrigerant. Refrigerants all tend to dissolve in oil (compressor sump) in percentages that
are directly proportional to increases in pressure and decreases in the T of the oil itself --- Charles' Law ---
(see Fig. 7).
Fig. 7
Charles' law diagram
The release of refrigerant tends to cool the oil and thus actually serves to oppose the release itself: for this
reason, it is advisable to switch on the crankcase heating elements, if available, during the evacuation
process. If a high % of refrigerant gets into contact with the Pirani gauge (vacuum sensor), it may "drug"
the sensitive element of the latter, rendering it inefficient for a certain period of time. For this reason, if no
machine for recovering refrigerant is available, it is nonetheless advisable to switch on the crankcase
heating elements and avoid applying a vacuum until the circuit has been adequately purged of refrigerant:
the refrigerant may in fact solubilize in the oil of the vacuum pump, undermining its
a long time (hours).
4.4
Charging positions (single point)
The best position for charging the air conditioners is the section between the thermostatic valve and the
evaporator; care should be taken to avoid fixing the thermostat bulb until the operation is complete: this is
important to ensure that the valve orifice remains open so as to allow the passage of refrigerant also
toward the condenser/receiver.
If possible, avoid the inflow of refrigerant into the compressor as this may cause excessive dilution of the
lubricant; in any case, first check the compatibility between the crankcase capacity and the required charge
volumes.
@DNOVA THX_R410A-IOM-1506-E
.
performance for
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