Analysis and Repair: The main causes of the above fault are as follows. (1) Abnormal power supply. (2) Compressor damage. (3) Control circuit failure. First, check that the power supply is normal, then confirm that the compressor is in good condition, which indicates a control circuit issue. Upon inspection, it was found that the overvoltage and undervoltage protection circuits were activated. The overvoltage comparator consists of the voltage comparator quad op-amp 1M339 IC1a, R16, R17, VRI, and the power voltage sampling output. The undervoltage comparator consists of the voltage comparator quad op-amp 1M339 IC1b, R18, R19, VR2, and the voltage sampling output. Under the control of the potential at pin 1 of IC1a and pin 2 of IC1b, it determines whether the +9V power source charges capacitor C8. Based on the above analysis, the DC power supply voltage of the operational amplifier 1M339 was detected to be +9V (normal), but the voltages at pin 7 of IC1a and pin 4 of IC1b did not match the normal values. Checking each component—R16, VR1, R17, R18, VR2, and R19—it was discovered that the contacts of VRI and VR2 were damaged. After replacing them, the fault persisted. Further testing of related components such as IC1b, R30, VT5, C7, R30, VT7, KR, and VD15 revealed that diode D15 had broken down.
Fault Symptoms: When starting heating mode, the compressor fails to start or operate, and there is no warm airflow from the indoor unit outlet.
Handling Method (for麦克维尔air conditioning): After replacing with new parts, the fault was resolved.
Source of Information: Beijing Xinke Air Conditioning After-sales Service Phone http://blog.sina.com.cn/xinkekt. Xinke split-type air conditioner, compressor does not start.