3-4
Refrigeration System
Low/High Side Leak or Undercharge
A loss of refrigerant can result in any of the
following:
1. Excessive or continuous compressor operation.
2. Above normal refrigerator/freezer compartment
temperature.
3. A partially frosted evaporator (depending on amount
of refrigerant loss).
4. Below normal refrigerator/freezer compartment
temperature.
5. Low suction pressure (vacuum).
6. Low wattage.
The condenser will be “warm to cool”, depending on the
amount of refrigerant lost.
In the case of a low side refrigerant leak resulting in
complete loss of refrigerant, the compressor will run but
will not refrigerate. Suction pressure will drop below
atmospheric pressure and air and moisture will be
drawn into the system saturating the filter drier.
If there is reason to believe the system has operated for
a considerable length of time with no refrigerant and the
leak occurred in the low side of the system, excessive
amounts of moisture may have entered the system. In
such cases the two stage service Dryer Filter part
number 5303918288 and vacuum procedure listed
under Refrigerant Leaks need to be followed to prevent
repetitive service.
If a slight undercharge of refrigerant is indicated and no
leak can be found after a thorough leak test, the charge
can be corrected without changing the compressor.
If a high side leak is located and some refrigerant
remains in the system it is not necessary to change the
compressor.
Testing for Refrigerant Leaks
If the system is diagnosed as short of refrigerant and
the system has not been recently opened, there is
probably a leak in the system. Adding refrigerant
without first locating and repairing the leak or replacing
the component will not permanently correct the difficulty.
The leak must be found. Sufficient refrigerant may have
escaped to make it impossible to leak test effectively. In
such cases, add a ¼” line piercing valve to the
compressor process tube. Add sufficient refrigerant
vapor to increase the pressure to 40 to 50 lb. per sq. in.
Check the low side for leaks. Run the compressor 2 or
3 minutes and check the high side for leaks. Recover
refrigerant using an EPAapproved recovery system.
Compressor Replacement
To check for contamination, obtain oil sample from old
compressor.
1. If the oil has burned odor, but no color change or
residue, then follow instructions on page 4-6
“Installing ANew Compressor”.
2. If oil has a burned odor and a sugar or gritty feel as
well as showing signs of contamination (dark color),
follow instructions in next section, To Flush The
System. Remove as much of contamination as
possible from system before installing new
compressor and filter-drier.
The line piercing valve (clamp-on type) should be
used for test purposes only. It must be removed
from system after it has served its purpose.
It is recommended that system be flushed with
dry Nitrogen. However, if refrigerant is used to
flush the system you must look at the serial
plate to see what type of refrigerant is used in
the system. This is the only refrigerant that can
be used to flush the system and it must be
recovered.
NEVER install a new compressor without first
checking for possible system contamination.