Abstract: Base on the characteristic of N.A. unitary air conditioner with non-bleed TXV as throttle valve, raised a fast restart solution for rotary compressor as well as the test validation. Firstly tested and analyzed the pressure change curve after the system is turned off, and then considered the application demand, proposed the technical solution by adding solenoid valve to rotary compressor. Thirdly, designed a new three-way valve by added a resetting spring on one side of the valve core. Lastly, accomplished the validation test of this solution on the unitary system which using a rotary compressor. According to the test result, the resetting design works well and the solution not only has good pressure maintaining function of HEX but also can achieve pressure balance within 3 min which lets compressor properly start up.

Key words: Rotary compressor, Pressure maintaining, Fast restart, Solenoid valve, Resetting spring