Abstract: Under severe operating conditions (high load, low temperature conditions, poor heat exchange), the air conditioner is prone to fall into the situation of poor lubricating oil and refrigerants return, and that will cause fatal damage to the operation of the compressor, leading to abnormal condition of the air conditioner system or even unable to run. The purpose of this paper is studying and analyzing the principles of the circulation of compressor oil and the migration of system refrigerants, based on the actual operating process of the air conditioner. Then, according to the test results of the lubricating oil return and refrigerants return of the air conditioner under different operating conditions, the results show that low-temperature sleep start up items, low-temperature defrost operation items, and high-load operation items are prone to poor oil and liquid return, then analyze the specific reasons for each item. It will provide guidance on household air conditioners and problem analysis.

Key words: Lubricating oil and refrigerants return, Compressor, Refrigerants migration, Household air conditioners