AUX air conditioner service manual
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of two back branches was obviously lower, so system was blocked when it was welded. Released
refrigerant, welded the system again and fault was eliminated.
Solution: welded the copper tube again, air conditioner run normally
Experience Conclusion: generally, air-stream sound was produced by over throttling, so we shall
analyze causes for throttling.
Case 12: Noise caused by bending of connection pipe
Unit Model: ASW-H12A4/M
Phenomena：Indoor unit made loud noise
Cause Analysis: opened the indoor unit and checked all components, we found that when compressor
run, it made noise, so air duct, motor and other components had no problem. We checked the
components of evaporator and listened to the sound and then found that noise was made by evaporator.
Gas pipe pressure was relatively lower than normal value; we continued to check and found that
connection pipe between indoor and outdoor units was folded badly.
Solution: after we replaced deformed part of connection pipe, the foregoing faults disappeared.
Experience Conclusion: only when air conditioner is in cooling and heating modes can noise be heard,
so gas pipe, motor and components have no problems. Check the system carefully, whistle is from
evaporator, which has been blocked with dirt and ice or blocked when the tube is welded. Decide the
fault position through listening, visual check and measuring temperature difference, and then deal with
the faults accordingly.
Case 13: Noise caused by improper installation
Unit Model: ASW-H12A4/ED
Phenomena：Abnormal noise could be heard after the air conditioner was turned on and run for some
time.
Cause Analysis: according to client, “coo” could be heard occasionally. Maintenance personnel
checked the air conditioner for about 3 hours, “coo” could be heard sometimes, we believed it was
from water collection pan in indoor unit when air condition was in cooling mode, and water drain pipe
might have some obstacles. We checked the pipe from indoor unit to outdoor unit carefully, and found
that water drain pipe in indoor unit was tied too tightly, and water couldn’t flow smoothly; water line
outside had a U type bending, so we considered that air flow returned sometimes and produced
abnormal sound. Because water pipe was not flat completely, water could still be drained and indoor
unit didn’t leak, it was very difficult to find the problem. We wrapped water pipe again, and adjusted
water pipe of outdoor unit, and then air conditioner could operate properly.
Solution: adjusted water drain pipe
Experience Conclusion: to deal with such kind of strange problems, maintenance personnel shall be
patient to check and consider in various aspects.
Case 14: Noise caused by improper outdoor unit installation
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