7
2.1 introDUction
The following should always be practiced with any sealed system that has been opened. ONLY OPEN THE SEALED SYSTEM AS
A LAST RESORT AND AS A FINAL DIAGNOSIS. Always check other areas of operation such as wiring, water supply, drain setup,
proper air ow, etc. before opening up the sealed system. Many times these areas can resemble sealed system problems. The
diagnosis of a sealed system can be determined by accurate pressure and temperature measurements.
Use a leak detection system that will detect R-134a refrigerant. Leaks need to be found on any leaking system BEFORE the 1.
repair takes place.
The drier must be replaced anytime the sealed system is opened. Always use a DCS drier. Failure to do so may cause repeated 2.
system failure in the future.
Limit time the system is opened. DO NOT EXPOSE THE OPEN SYSTEM FOR MORE THAN 15 MINUTES. This will prevent a sealed 3.
system failure. Leave replacement parts sealed and/or pressurized until ready to install.
The compressor must be replaced if there is a low side leak. Moisture has been drawn into the system if the unit has been 4.
running for an extended period of time. Be sure to ush the system with dry nitrogen gas and evacuate to 50 microns before
re-charging (see Section 2.2, Low Side Leaks).
A new evaporator assembly must be ordered if the capillary tube is found to be plugged or severely restricted. Restrictions 5.
cannot be ushed out.
Be sure to purge the system after nal brazing. This will ush out any air or moisture that may have entered the system before 6.
being absorbed into the refrigerant oil.
IMPORTANT
Testing of the electrical system, defrost system, controls, and air ow should be performed before entering any sealed system.
What may rst appear to be a system component failure may be only a simple control, air ow, electrical, or defrost system
problem.
2.2 loW SiDe leakS
Low side leaks consist of a break in the system at the evaporator, low side (suction) return line, or accumulator. If a leak is found in
any of these areas, moisture has probably entered the system. The compressor and drier will have to be replaced and the system
will need to be ushed thoroughly with nitrogen gas and evacuated to 50 microns before re-charging.
2.3 high SiDe leakS
High side leaks consist of a break in the system at the condenser, high side tubing, drier, or capillary tube. If a leak is found in any
of these areas, the system can be ushed with nitrogen gas, evacuated to 50 microns, and re-charged.
2.4 reStricteD capillary tUBe
Moisture or other contaminants that enter the system can cause deposits in the system. These deposits will usually collect in the
capillary tube and form a restriction that cannot be completely removed by ushing. If the capillary tube is found to be restricted,
the evaporator, compressor, condenser, and drier should all be replaced.
SEALED SYSTEM
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