R22 upright or upsidedown?

If the sight glass is foamy, stop what your doing, the system is contaminated with moisture. Chances are the compressor is gonna be toast. First reclaim the refrigerant, second replace the filter drier. third triple evacuate the unit with a vacuum pump, until the pressure gets down to below 1000 microns.(400 is ideal, but I doubt this system will ever see that without replacing the compressor). Fourth, if these tasks are beyond your abilities, call a service company, or have the unit replaced. The reason the compressor shuts off after two minutes is because theinternal overload protector has tripped, this means the compressor is drawing too many amps, since you have replaced the capacitor I cansafely assume, either the internal components of the compressor have been damage by the acid created by the presence of moisture in the system, or the filter/drier, or strainer (internal) have been plugged with debris. Either way it will take several hours of work to save it, or a few hours to replace it. Sorry to have to give ya the bad news.......good luck!

STOP what are the pressures. you dont want to add freon just yet

Attach the service gauge to the low side and position the refrigerant container upright.