In today competitive market, Seasonal Energy Efficiency Ratio (SEER) and sound rating of the out door unit of an air conditioning system are strong marketing and selling parameters. Air conditioning systems consist of an indoor unit and an outdoor unit. The sound of the indoor unit is mainly radiated by the blower or fan of the unit. The outdoor unit has three major components, namely, a compressor, a condenser coil and a fan. In general, the sound power levels produced by the outdoor unit are dominated by the fan, and in some cases, the fan and the compressor. In more recent designs, significant improvement has been made in the sound performance of the fan itself, resulting in a challenge to compressor manufacturers to produce quieter compressors. In this case, compressor-system interaction becomes a serious issue with reference to noise generation. The vibration energy of the compressor is transmitted to the system through the suction and discharge tubes, and the mounting feet. Air conditioning manufacturers are faced with the challenge of eliminating these sources of excitation to improve the sound rating and, more importantly, design better quality products. The main object of the paper is to modify the design of the discharge tube using an experimental iterative approach. A reduction of 2 dB has been achieved in the total sound power level of the system. On the dominant one third octave bands, sound power levels are reduced up to 7 dB. The results of this investigation will serve as the basis for the development of an analytical designed tool for air conditioning system design. These results were validated on four systems.
