Electrolux Wine Cooler / Beverage Center, Service Manual

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D - Refrigeration System
Verify Refrigerant Type In The
System
For example, hoses that were used for a
refrigeration system operating on R-12 may contain
small quantities of mineral oil which can block the
capillary tube in a system operating on R-134a. As
little as one milligram may be sufficient to cause a
blockage. In addition, sealed system components
that have been used with CFC systems must not
be used with R-134a systems. These components
may contain residual amounts of refrigerant and oil
which could damage an R-134a system.
NOTICE
Instructions given here are furnished as a guide.
Persons attempting to use these instructions to
make repairs to the sealed refrigeration system
should have a working knowledge of refrigeration
and previous training on sealed system repair.
CAUTION
R-134a and R-12 are completely incompatible.
Before starting any sealed system repair, it is
extremely important to check serial plate of
product to verify the type of refrigerant in the
system.
Dedicated Equipment
R-134a must not be mixed with other types
of refrigerants. R-134a must be recovered in
dedicated and properly identified recovery bags
and tanks.
It will be necessary to check with the manufacturer
of your recovery equipment to determine
R-134a compatibility. Some recovery equipment
manufacturers have changeover instructions
for switching between refrigerant types. Protect
yourself and your equipment by following all
manufacturer guidelines.
Also, ensure that your refrigeration hoses
are specified for use with R-134a refrigerant.
Research has shown that compounds in standard
refrigeration hoses may enter sealed systems
and ultimately restrict the cap tube in an R-134a
system.
R-134a Refrigeration Systems
The sealed refrigeration system will consist of the
same basic components being utilized in the R-12
systems.
There is a 10% to 15% discharge pressure
increase using R-134a, with a 5% to 10% decrease
in suction pressure when compared to the same
product with an R-12 system operating at 90°F
(32°C) ambient temperature conditions. Lower
suction pressures result from the lower density of
R-134a refrigerant which effects refrigerant flow
rate. R-134a systems commonly operate in a 1”-2”
vacuum on the suction side.
Products using R-134a refrigerant will generally
have a longer capillary tube to maintain a similar
flow rate and some models will have a larger
condenser to reduce the discharge pressures and
lower start-up sound transmission.
Miscibility of R-134a and
Ester Oil
A special synthetic oil known as Ester oil is used
as a lubricant in refrigeration systems operating
on R-134a. Ester oils are produced from alcohols
and fatty acids and are available in several
different variants. Ester oils have a pleasant aroma
reminiscent of fruit.
Ester oils generally include various types of
additives for improving certain properties such
as viscosity, temperature sensitivity, etc. These
additives are often aggressive, and skin contact
with Ester oils should therefore be avoided.
One of the most important requirements made
on a refrigerant system is that the oil mix with the
refrigerant. Since mineral oil and ordinary synthetic
oil DO NOT mix with R-134a, Ester oil is used for
lubrication. Ester oil dissolves in R-134a.
Ester oil is broken down by chlorine and cannot
be used with R-12 (R-12 contains chlorine) or any
other compound containing chlorine. Therefore,
R-134a refrigeration systems have virtually
no tolerance for chlorine molecules from CFC
refrigerants (R-134a is an HFC and contains no
chlorine).
CAUTION
During R-134a service, it is extremely
important to avoid using equipment that may
contain residual amounts of mineral oil, CFC’s
or HCFC’s which could enter and contaminate
the sealed system.