Manual for Refrigeration Servicing Technicians - UNEP - Division of ...

5
Retrofitting
MVAC retrofitting procedure
Refer to the manufacturer’s retrofit procedures whenever available.
The following are recommended procedures, specifically for retrofitting R12
MVAC systems to a R134a system:
1 - Check for leaks using a hand-held leak detector (refer also to SAE
J1628: 2003) and set to detect R12 and/or use the soap bubble
test. Make repairs if necessary.
2 - Run the vehicle to obtain suction and discharge pressures, which
should be noted, and check again for leaks.
3 - Recover the entire refrigerant from the system following the
standard procedure for CFC refrigerant recovery and store in a
specified refillable container which is properly labelled.
4 - Remove the compressor from its mounting bracket and drain its
lubricating oil.
5 - Rinse the internal parts by pouring alternative oil for new refrigerant
into the compressor and manually rotating the compressor shaft.
The amount of oil for rinsing is about 50% of the recommended
factory oil charge.
6 - Repeat the oil rinsing procedure as necessary.
7 - Pour the proper amount of alternative refrigerant oil into the
compressor as per the original equipment manufacturer (OEM)
recommendations, and cap the suction and discharge lines until the
system is ready for re-assembly.
8 - Flush the entire system with oxygen-free dry nitrogen and any
cleaning agent not containing an ODS.
9 - Carry out tightness tests for each component for leaks. Repair or
replace if necessary.
10 - Replace the expansion device and the filter drier with ones that are
compatible with the alternative refrigerant.
11 - Change all flare type to O-ring type fittings.
12 - Replace all O-ring seals on pipes and hoses with those approved
for R134a and PAG oils.
13 - Re-install and assemble system components.
14 - Modify the access valves/fittings to accept only the new alternative
refrigerant fittings.
15 - Evacuate system to at least 1000 microns using the appropriate
vacuum pump and an electronic vacuum gauge. Make corrections if
necessary.
16 - Charge the system with the alternative refrigerant (SAE J1657: 2003)
as recommended by the manufacturer whenever possible. Notice
that the optimum charge will change when systems are retrofitted.
17 - Run the vehicle to observe the system operation and check again
for leaks.
18 - Compare the new set of performance data to that obtained when the
system was still using CFC.
19 - Label the system clearly.
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