26 PB
R-410A SEALED SYSTEM REPAIRS
Restricted Refrigerant System
Troubleshooting a restricted refrigerant system can be difcult. The following procedures 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 equalize very slowly.
Gauges connected to a completely restricted system will run in a deep vacuum. When the unit is shut off, the gauges will not
equalize at all.
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 speci cation. 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 primarily on a system in the cooling mode.
Figure 603 (Restricted System)
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