### Fault Phenomenon:
After turning on the power and starting the unit, normal heating operation occurs, but during cooling mode, frequent shutdowns occur, and the temperature does not decrease.
### Fault Analysis:
The normal heating function after startup indicates that the mechanical and electrical systems of the air conditioner are basically functioning correctly. The focus should be on checking the temperature detection circuit of the refrigeration system, as improper operation of this circuit can cause issues even if the refrigeration system is working normally. If the temperature sensing is abnormal, the temperature will not drop accordingly.
### Fault Inspection:
1. **Observation After Startup:** It was found that the compressor remains in a long-term shutdown state. After adjusting the temperature button, it only works for a short while before shutting down.
2. **Check Power Supply Connector JP21:** The connector for the compressor power supply (JP21) was checked and found to be normal, with no sparking at the relay, indicating that the power control circuit is functioning properly.
3. **Temperature Sensing Circuit Check:** When holding the temperature-sensing tube by hand, the compressor started slowly. The components R95, C66, C65, R96, and RT3 (temperature sensor) in the temperature detection circuit were inspected, and it was discovered that capacitor C66 had broken down and short-circuited.
4. **Replacement and Repair:** A new 0.2F capacitor replaced the damaged C66 capacitor, resolving the fault.
### Prompt:
The temperature detection circuit is composed of RT3, R95, etc. In the circuit, RT3, R95, and R96 form a voltage divider circuit that divides the +5V voltage and sends the divided signal to pins 17 and 18 of the microprocessor IC14. After internal processing, a control signal is output from pin 31 to control the operating state of the compressor. When C66 breaks down and shorts out, it causes the upper limit of temperature sensing to rise, leading to the aforementioned fault.
### Additional Information:
For further reference, please visit the Beijing Midea Air Conditioning After-sales Service hotline or website: [http://blog.tianya.cn/blogger/blog_main.asp?BlogID=3760772](http://blog.tianya.cn/blogger/blog_main.asp?BlogID=3760772).
**Case Summary:** The Midea floor-standing air conditioner can heat normally but experiences frequent shutdowns during cooling mode.