**McQuay Air Conditioning: Poor cooling effect due to flattened connecting pipes**
**Fault Phenomenon:** Poor cooling effect
**Cause Analysis:** After the new installation of the air conditioner, abnormal noise was heard indoors. During the three-minute trial operation and in the fan mode, no abnormal noise was detected. However, when the compressor started, the indoor evaporator emitted an unusual refrigerant airflow sound, which was quite loud. Upon inspection, it was found that both the high-pressure and low-pressure pipes at the connection point of the indoor evaporator were three-quarters flattened. The issue occurred at the connection between the indoor evaporator output pipe and the condenser copper pipe (the joint is not a threaded copper pipe).
**Maintenance Measures:** Replace the connecting pipe.
**Experience Summary:** In cases like this, the airflow noise is mainly caused by the restricted flow of refrigerant. A detailed inspection is necessary to identify where the pipe has been flattened. This issue is primarily due to unprofessional pipe bending during installation.
**Source of Article:** [http://blog.tianya.cn/blogger/blog_main.asp?BlogID=3774629](http://blog.tianya.cn/blogger/blog_main.asp?BlogID=3774629)