Friedrich SM21L30-A, Service Manual

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14
A quick check for either condition begins at the evaporator.
With a partial restriction, there may be gurgling sounds at the
metering device entrance to the evaporator. The evaporator
in a partial restriction could be partially frosted or have an ice
ball close to the entrance of the metering device. Frost may
continue on the suction line back to the compressor.
Often a partial restriction of any type can be found by feel,
as there is a temperature difference from one side of the
restriction to the other.
With a complete restriction, there will be no sound at the metering
device entrance. An amperage check of the compressor with a
partial restriction may show normal current when compared to the
unit specification. With a complete restriction the current drawn may
be considerably less than normal, as the compressor is running in
a deep vacuum (no load). Much of the area of the condenser will
be relatively cool since most or all of the liquid refrigerant will be
stored there.
The following conditions are based primar ily on a system in
the cooling mode.
RESTRICTED REFRIGERANT SYSTEM
Troubleshooting a restricted refrigerant system can
be diffi cult. The following proce dures are the more
common problems and solutions to these problems.
There are two types of refrigerant restrictions: Partial
restrictions and complete restrictions.
• A partial restriction allows some of the refrigerant to
circulate through the system.
• With a complete restriction there is no circulation of
refrigerant in the system.
• Restricted refrigerant systems display the same
symptoms as a “low-charge condition.”
• When the unit is shut off, the gauges may equal ize very
slowly.
• Gauges connected to a completely re stricted system
will run in a deep vacuum. When the unit is shut off, the
gauges will not equalize at all.
REFRIGERANT CHARGING cont’d