Electrolux E32AR75FPS, Техническое и сервисное руководство

Страница: 50 / 112

Sealed System
5-6
Low/High Side Leak or
Undercharge
A loss of refrigerant can result in any of the
following:
1. Excessive or continuous compressor operation.
2. Above normal freezer compartment temperature.
3. A partially frosted evaporator (depending on amount
of refrigerant loss).
4. Below normal freezer compartment temperature.
5. Low suction pressure (vacuum).
6. Low wattage.
The condenser will be “warm to cool”, depending on the
amount of refrigerant lost.
In the case of a low side refrigerant leak resulting in
complete loss of refrigerant, the compressor will run but
will not refrigerate. Suction pressure will drop below
atmospheric pressure and air and moisture will be drawn
into the system, saturating the filter drier. A system with
R-134a refrigerant and ester oil will become saturated
with moisture much faster than a system with R-12 and
mineral oil. Therefore, you must obtain a sample of the
oil and check with an oil test kit to determine the amount
of contamination. You will find that the oil in an R-134a
system will have to be replaced after most low side
leaks.
If there is reason to believe the system has operated for
a considerable length of time with no refrigerant and the
leak occurred in the low side of the system, excessive
amounts of moisture may have entered the system.
In such cases, the two stage service Dryer Filter part
number 5303918288 and vacuum procedure listed under
Refrigerant Leaks, need to be followed to prevent
repetitive service.
If a slight undercharge of refrigerant is indicated and no
leak can be found after a thorough leak test, the charge
can be corrected without changing the compressor.
If a high side leak is located and some refrigerant
remains in the system it is not necessary to change the
compressor.
Precautions For Charging Sealed
Systems
Overcharging a refrigeration system with refrigerant can
be dangerous. If the overcharge is sufficient to immerse
the major parts of the motor and compressor in liquid
refrigerant, a situation has been created which, when
followed by a sequence of circumstances, can lead to
the compressor shell seam separating.
When a hydraulic block occurs, the compressor is
prevented from starting. This condition is known as
locked rotor. Electric current continues to flow through
the compressor motor windings which become, in effect,
electric resistance heaters. The heat produced begins
to vaporize the excess refrigerant liquid, causing a rapid
increase in system pressure. If the compressor
protective devices fail, pressure within the system may
rise to extremes far in excess of the design limits.
Under these conditions, the weld seam around the
compressor shell can separate with explosive force,
spewing oil and refrigerant vapor, which could ignite.
To eliminate this exceedingly rare but potential hazard,
never add refrigerant to a sealed system. If refrigerant
is required, evacuate the existing charge and recharge
with the correct measured amount of the refrigerant
specified for the system.
Always make sure your equipment is in good condition
and all manufacturer’s instructions are followed to
prevent the accidental rupture of a hose, connection
fitting, or a tank which could cause a serious injury. Run
equipment until system has reached 13 inches of
vacuum. Shut system down and allow to set for two
minutes, if pressure remains below (0) pounds per
square inch, disconnect equipment and proceed. If
pressure does not stay below (0) pounds per square
inch, repeat above procedure until all refrigerant is
removed and system remains in a vacuum.
Flushing The System With
Nitrogen
It is recommended that system be flushed with dry
Nitrogen. However, if refrigerant is used to flush the
system you must look at the serial plate to see what
type of refrigerant is used in the system. This is the only
refrigerant that can be used to flush the system and it
must be recovered.