Viking DFUW244CL, Service Manual

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3.4 R-134a
The following CAUTIONs should be read before proceeding
The dual zone wine cooler utilized R-134a refrigerant.
R-134a and R-12 are completely incompatible. Extreme care should be taken to use only dedicated
equipment not only when evacuating and recharging the system but for all system repair.
With the possible exception of the vacuum pump, all service equipment that comes in contact with
R-134a during evacuation and recharging must be dedicated. Accordingly, R-134a will require a
dedicated charging cylinder, manifold gauge set, process tube adaptors, and hoses. Any residual mineral
oil or other tools used for system repair must be cleaned thoroughly before using R-134a / Ester oil
systems.
CAUTION Ester oil is synthetic oil used as a lubricant in R-134a systems. Ester oils include various
types of additives for improving viscosity, and temperature sensitivity. These additives are often
aggressive and skin contact should be avoided.
It is important to note that Ester oil and mineral oil do not mix
If a vacuum pump with mineral oil is used to evacuate an R-134a system, it is absolutely essential to
have a shut-off valve between the pump and the manifold gauge. The hand valve must be closed during
all times when the vacuum pump is not operating. This prevents the migration of mineral oil vapor into
the R-134a / Ester oil system. If the vacuum pump should stop during evacuation, the hand valve must
be closed immediately.
Insure that all refrigeration hoses are specified for use with R-134a refrigerant. Research has shown
that compounds in standard refrigeration hoses may enter the sealed systems and eventually restrict the
capillary tube.
15
2010 - Viking Preferred Service SMR-0005