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6
2.3 High Side Leaks
High side leaks consist of a break in the system at the compressor, condenser, discharge tubing,
drier, or capillary tube. If a leak is found at any of these areas, replace or repair the leak. Flush
the system with nitrogen gas, evacuated to 50 microns, and recharged.
2.4 Restricted Capillary Tube
Moisture or other contaminants that enter the system can cause non condensable deposits in
the system. These deposits will usually collect in the capillary tube and form a restriction that
cannot be removed by flushing. If moisture is found in the system, the entire system has been
compromised due to the unstable relationship between ester oil and moisture.
For non-moisture related restrictions: If the capillary tube is restricted, typically the restriction
is at the inlet end, inserted into the drier. This can be repaired by cutting off approximately 1”
of capillary tube, inserting the cut end into a new drier, and re-soldering the joint. If the leak is
elsewhere in the capillary tube, it would be best to replace the evaporator / heat exchanger
assembly, pull a satisfactory vacuum and recharge.
2.5 Access/Process Valves
A temporary access valve can be used to service or evaluate the system. From these temporary
access valves, you can recover, evacuate, and re-charge the system. The access valve will be
installed on the compressor’s process tube (low pressure side). Be sure to cap off the access
valve if you have not completed servicing. This will prevent contamination of the system and
temporarily prevent refrigerant from leaking. After servicing is complete, the temporary valve
must be removed from the sealed system. A pinch-off tool can be used to close off the process
tube downstream from the valve piercing. Once this is done, the temporary valve can be
removed and the pierced section of the process tube cut off. The open end of the process tube
can now be soldered/brazed shut to seal the system. Be sure to leak check after brazing.
If a permanent soldered/brazed Schrader valve is used, the cap must be snugged firmly after
service is completed.
2.6 Evaporator Frost Pattern
In the past Marvel has always recommended not using a gauge set to determine system
capacity and pressures. The amount of refrigerant in these systems is so minute, that any
amount of charge lost during gauge installation or removal can be detrimental to the
refrigeration system.
It was determined that checking the frost pattern on the evaporator was always a good
indicator for reference.
The following procedure was recommended to check a typical cold plate evaporator:
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