Chunlan cabinet-type air conditioner, about 15 seconds after the machine is turned on, the low voltage indicator light turns on.
**Fault Phenomenon:** Beijing Chunlan Air Conditioning After-sales Service Hotline; For the Chunlan cabinet-type air conditioner, both indoor and outdoor units automatically shut down about 15 seconds after being turned on. The low voltage indicator light on the operation panel lights up, and repeated operations result in the same fault.
**Analysis and Repair:** Based on the fault phenomenon, the illumination of the low-voltage indicator light indicates that the protection circuit has been activated. During inspection, the first step should be to check the power supply. Upon checking, the three-phase power voltage and the secondary voltage after transformer step-down were found to be 6.3V and 12.3V respectively, which are normal. To prevent secondary faults during powered testing and avoid frequent start-ups of the main unit, the signal power connection terminals between the indoor and outdoor units can be left suspended. This way, when powered on, the relay cannot engage, and the main unit will not start running. It was measured that the voltage at pin 7 of the IC was high, and further checks revealed unstable voltage at pin 6 of the IC. A faulty filter capacitor C4 was identified upon inspection. After replacing C4, the fault was resolved.
Beijing Chunlan Air Conditioning Repair Center, August 10, 2011.