Model KFR-48LW Changhong air conditioner works normally in cooling mode during summer but fails to heat during winter.
Fault Phenomenon: The air conditioner cools normally in summer but does not heat in winter.
Fault Detection: This air conditioner is a heat pump type. It works fine in cooling mode during summer, indicating that the compressor power supply and control circuit are basically normal. The fault may be due to the electromagnetic four-way valve failing to switch or improper temperature setting. When the air conditioner's temperature control range is 16~30℃, it was found that the set temperature of 24℃ is correct. The control circuit of this air conditioner uses IC101 (CPU) as the control core to complete relevant control input data and output relevant control signals to the inverse driver IC106 and IC105. After inversion, IC106 and IC105 output low levels, connecting the corresponding relays. Pin 15 of IC106 and pin 16 of IC105 control the compressor, four-way valve relay RY101 and RY104 respectively. Upon checking, pin 16 of IC105 was at a low level, but RY104 did not engage, indicating that RY104 was damaged, causing the four-way valve to fail to switch. After replacing relay RY104, the fault persisted. Further inspection revealed that the four-way valve was jammed and unable to switch.
Repair Measures: After replacing the four-way valve, the heating function returned to normal.
Beijing Changhong Air Conditioner Repair Center, August 10, 2011.