Friedrich V(E, Service Manual

Page: 18 / 44

18
Overcharged Refrigerant Systems
Compressor amps will be near normal or higher.
Noncondensables can also cause these symptoms. To
confi rm, remove some of the charge, if conditions improve,
system may be overcharged. If conditions don’t improve,
Noncondensables are indicated.
Whenever an overcharged system is indi cated, always
make sure that the problem is not caused by air fl ow
problems. Improper air fl ow over the evaporator coil may
indicate some of the same symptoms as an overcharged
system.
An over charge can cause the compressor to fail, since it
would be "slugged" with liquid refrigerant.
The charge for any system is critical. When the compressor
is noisy, suspect an overcharge, when you are sure that
the air quantity over the evaporator coil is correct. Icing
Restricted Refrigerant Systems
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 specifi 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 primar ily on a system
in the cooling mode.
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.
of the evapora tor will not be encountered because the
refriger ant will boil later if at all. Gauges connected to
system will usually have higher head pressure (depending
upon amount of overcharge). Suction pressure should be
slightly higher.