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moisture and keeps them plugged with the right plug till it is required to be used in the
repair.
iii) Do not use lubricating oil or refrigerant from chlorine based sealed system into R134a
system.
iv) Use sweep charging method (explained in detail in the next section) for charging of R134a
based systems after repair as it is more effective in removing the contaminants from the
sealed system.
v) Always replace the filter-drier in all sealed system repairs of R134a based systems
vi) Do not use the replacement compressor if its stubs are not plugged properly and do not
remove the plugs till it is time to braze the tubing to the stubs.
vii) Do not use manifold gauges during purging and charging of system.
CAUTION
If the above precautions are not followed it will result in the
premature compressor failure or complete system failure.
SWEEP CHARGING PROCEDURE FOR SEALED SYSTEM
REPAIR OF GNF REFRIGERATOR
The following are the main steps in the sweep charging of GNF refrigerator sealed system.
1) One or two access valves are attached to the sealed system. (The number of valves
depend on whether the compressor is operational or not.
2) The existing refrigerant charge is purged from sealed system in to a recovery bag.
3) Repairs are made to the sealed system taking all the precautions as required in repair of a
R134a refrigerant based sealed system.
4) The filter drier is replaced by a new filter drier.
5) The brazed joints on the high side are visually inspected for leaks.
6) The high side components are back flushed.
7) Four ounces of liquid refrigerant are metered into the sealed system.
8) A leak check is performed on the newly brazed joints in the high side of the system.
9) The compressor is run to circulate the sweep charge throughout the system
10) The refrigerant containing the contaminants is purged form the high side access valve in to
a recovery bag.
11) The system is finally charged with the prescribed amount of new refrigerant.
The sweep charging method is superior to other charging methods in removing the
contaminants (moisture and non condensable matter) from the sealed system.
The details of the sweep charging procedure is given in the flow charts No. 1 to 10
REPLACING R134a COMPRESSORS
1. CAUTION: Never open replacement compressor studs to the air for longer than 10
minutes.
2. Carefully inspect rubber plugs in the service replacement compressor studs. If the plug
appears to have been removed or tampered with, DO NOT USE THE COMPRESSOR. Get
another one.
3. Clean compressor studs with plugs still in them.
4. Install into system last. Braze into system within ten minutes.
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