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Chapter 5: Guide for Maintenance of
R134a Refrigerator
I. Property of the R134a refrigerant
R134a, also named as tetrafluoroethane, is one of the hydrofluorocarbon (HFC for short), The
molecular weight of it is 102, and its structural formula is CH
2
FCF
3
. It is colorless transparent liquid,
without turbidity and foreign odor. Its ozone depleting potential (ODP: ozone depletion potential) = 0. and
its greenhouse effect potential (GWP: global warming potential) = 1300. ASHRAE safety class: A1. I is
non-toxic and non-flammable.
II. Maintenance technology of R134a refrigerator
1. General requirement: no matter whether there is leakage of the system, reliable earthing for all the
equipment is necessary when filling the refrigerant, so as to avoid sparks resulting from possible static
electricity. Besides, all the wiring must be firm, and wrong wiring is not permitted.
2. Firstly, check whether there is fire source around, and keep favorable ventilation;
3. Get the equipment and fittings ready which are specially used for maintenance;
4. Check the safety of maintenance equipment and main supply;
5. Check whether there is leakage, loose for the emptying clamp, and adjust it to the proper position;
6. Lead the exhaust pipe to the outdoor, get the emptying clamp stuck at the dry filter, start the
compressor, and stop after 5-minute operation. Vibrate the compressor, so as to discharge the
isobutane dissolved with lubricating oil. After 3-minute suspension, re-plug to operate for 5 minutes, so
as to minimize the isobutane content in the pipe system;
7. Cut off the power supply, seal the air vent of dry filter, get the special emptying clamp stuck at the low
voltage tube of the compressor, use the R134a vacuum pump to evacuate, and operate for 10 minutes;
8. Remove the compressor, dry filter using pipe cutter, and adopt nitrogen to blow the pipe for more than
5 seconds;
9. Change the R134a compressor, dry filter, and weld each interface by gas welding;
10. Blow the nitrogen to check the leakage, with nitrogen pressure no larger than 0.8Mpa, and use soap
water to check the leakage;
11. Discharge the nitrogen, and evacuate for more than 20 minutes, so that the vacuum degree will
reach up to specified value;
12. In order to ensure the accuracy of recharge, electronic scale shall be adopted for the weighting
during the filling. Plug the refrigerator to operate;
13. There is no abnormal seal;
14. Use suds to check leakage of the seal;
15. Plug the refrigerator to operate, and test its performance.
III. Precautions
1. If it is required to change the compressor during repair, the recharged amount shall be specified value;
no need to change the compressor, the recharged amount shall be 90% of the specified value.
2. It is not advisable to open the refrigerating system to operate at home by the users in principle,
because it is dangerous.
IV. Servicing installation and tools
1) R134a evacuating placer
2) Electronic scale
3) Emptying clamp
4) Sealing clamp
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