Bosch B22CS50SNW-01 General Repair - Instruction page 23

2.12.3 R 134a
Important information when carrying out repairs:
Work on an open R134a refrigeration circuit should be concluded as
quickly as possible. These refrigeration circuits use a synthetic ester
oil which quickly combines with air humidity. If possible, the
refrigeration circuit should not be open for longer than 30 min,
otherwise acid will form due to an excessively high concentration of
water in the oil.
Do not leave an R134a refrigeration circuit open for
longer than 30 min!
Before a refrigeration circuit can be refilled, it must be evacuated.
A vacuum is generated in the refrigeration circuit by a pump. The
humid air must be removed from the circuit. The humidity can
evaporate in the vacuum even at room temperature. The water vapour
which was produced is drawn out of the circuit together with the air.
The refrigeration circuit is evacuated on the intake side via the service
pipe on the compressor and on the pressure side via the service
connection on the dryer. The refrigeration circuit should be evacuated
in this way for approx. 10 min.
Evacuating and filling station for R134a;
The evacuating and filling station is used to check, evacuate and fill
refrigeration circuits with the refrigerant R134a. The evacuating and
filling station features a vacuum pump and a heatable filling cylinder.
The fitter's aid features a blue pressure gauge for measuring the
pressure on the intake side, a red pressure gauge for measuring the
pressure on the pressure side and a tormeter. The tormeter measures
the range between 1 bar and a vacuum of 0 bar and is used to display
the low pressure in the refrigeration circuit during the evacuation
process. The values can be read off very accurately on account of the
wide scale. The fitter's aid features several valves. The valve with the
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blue switch is for the intake side. The valve with the red switch is for
the pressure side. The black valve is the filler valve and the yellow
valve is the one which leads to the vacuum pump. The tormeter is
required during the evacuation process and can be disabled with the
valve situated below.
Filling the filling cylinder;
The amount of refrigerant required to repair a refrigeration circuit must
be put into the filling cylinder prior to the evacuation process. To do
this, close all valves on the fitter's aid. The refrigerant bottle is
connected to the end of the red hose. Open the red valve and the
black valve and hold the refrigerant bottle with the extraction valve at
the bottom. Liquid refrigerant can then flow into the cylinder. The glass
tube in the middle of the cylinder is used as a level indicator. The
pressure gauge situated on the cylinder indicates the pressure in the
cylinder. Select the appropriate scale by rotating the scale ring. Read
off the required amount on the scale. Close the red valve and the
black valve. Always fill the cylinder with adequate refrigerant so that
there is approx. 25 g of refrigerant left in the cylinder after the filling
process. Mark the required amount of refrigerant on the scale ring. Fill
the cylinder with refrigerant. When the refrigerant bottle is removed,
refrigerant which collected between the red valve and refrigerant
bottle will escape.
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