First thing ro do is realize that you cannot diagnose AC concerns from only low side pressures.... Your low side pressures aren't doing anything abnormal. What is abnormal is the rapid clutch cycling times.... and the most common (but not the only) cause of rapid cycling is a low refrigerant charge...
The correct way to proceed from a proper diagnosis of a low charge (using both high and low side gauges), would be to fecover the refrigerant and pull a deep vacuum on the system. Once vacuum reaches ~27 inches, the pump is turned off and the valves closed and we observe the gauges... If and how fast the vacuum drops will have a bearing on our repair strategy.
Venting refrigerant of any sort to atmosphere is illegal in my province - something I agree with and will support to my last breath (think about it....). Topping off with cans from Partz R Us has the possibility of causing system damage (especially in the case of a misdiagnosis) or contributing to pollution.
While I applaud and even help DIYers with auto repairs (and saving money), some auto repair efforts are inappropriate for those without specialized knowledge and equipment.