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D - Refrigeration System
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 EPA
approved recovery system.
NOTE
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.
Compressor Replacement
CAUTION
NEVER install a new compressor without first
checking for possible system contamination.
To check for contamination, obtain oil sample from
old compressor.
• If the oil has burned odor, but no color
change or residue — follow instructions in
section "Installing A New Compressor".
• 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.
To Flush The System
NOTE
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.
CAUTION
Use extreme care when using Dry Nitrogen to
flush systems. Pressure in nitrogen cylinder
could be as high as 2000 psi. Nitrogen
cylinder must be equipped with approved
pressure regulator and pressure relief valve.
Ensure that your hoses have adequate ratings
for pressure involved and that all of your
equipment is in good condition.
The end of the flushing hose on this tank
regulator must be equipped with a hand shut-
off valve (Robinair No. 40380). Close hand
shut-off valve and adjust nitrogen regulator
to correct pressure before proceeding with
flushing procedure.
To Use Dry Nitrogen To Flush The System:
1.
Remove compressor and filter-drier.
Connect process coupling to outlet tube of
condenser.
2.
Fasten cloth over other end of coil to
prevent old oil from spraying over room.
3.
Connect hand shut-off valve on flushing
hose to process coupling.
4.
Slowly open hand shut-off valve and allow
nitrogen to flow through condenser until
discharge is clear.
CAUTION
DO NOT exceed 300 PSIG.
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