Your picture of the hose I think is what was pissing green coolant. I also replied to this thread for a back story if you can offer any help.Seems they kept the same setup in the gen2s but you have to remove the engine or radiator to get access. No low pressure cutout switch or drying tank like the older units.
The system resembles those used in many aftermarket systems which used a temperature sensor located on the expansion valve (or controlled orifice) on the suction line where it enters the evaporator(s). A low refrigerant charge and lower than spec pressure on the suction line will cause external freezing and blockage of the evaporator coils preventing cooling so a temperature sensor will cut power to the compressor clutch and the electric radiator fans if the coolant temperature is within specs.
One would think ice forming on the evaporator coils is a good thing- it is not because at best it will cause frost and only temporarily block the coils to air flow - but the lower mass charge does not have the capacity to extract the mass of heat from the car interior so all you get is a rapid cycling effect that is insufficient to cool the air and extract heat from the mass within the interior. Compressor off, evaporator heats up, valve/coils unfreeze, compressor on, suction pressure rises, lines refreeze, compressor off.......xxxxx
Problem does not appear to be the high pressure cutout - if high pressure is above 400+ and the compressor cuts out and then cuts in again once the high pressure side drops.....it appears to be working in its role as a safety device.
Normal operation is that with the compressor off and allowed to sit for a while both low and high sides should equalize with the same pressure readings. Once in operation the suction (larger pipe) pressure lowers and the exhaust (smaller pipe) pressure rises. A low refrigerant charge will cause the low side to drop below pressure, freeze the coils (open the temps sensor) and cutout the compressor, but this will also cause a lower than spec exhaust (high pressure side).
Seems this is not what OP describes . i.e. a low charge, low pressure side but instead with a higher than spec high pressure side. Regardless of whether a system uses a low pressure cutout switch or a temperature monitoring switch, the high temperature switch should never be cycling the compressor and at 400+ p.s.i. this appears to be the case. So as mentioned previously the problem is likely air in the system which will cause the high side to skyrocket even if the low side is within specs.....with air comes humidity (moisture) and even if the volume of air alone only marginally boosts the high side pressure, the small traces of moisture (absent a dryer or a dryer which has become saturated) can be enough to internally block the small openings in the expansion valve or orifice and stop the flow of refrigerant while the compressor is constantly compressing what little refrigerant there is and pulling a partial vacuum on the suction side until the high pressure becomes so great the cutout kicks in.
My .02 At this point the system needs to be serviced by evacuation until the air is expelled and the moisture removed before refilling - continued addition of refrigerant while the high side is reading 400+ is simply not wise - should the high pressure cutout fail and you exceed test specs something has to give and either the compressor will fail, a line will rupture or a connection/fitting will blow at the under hood condenser or feeding the interior evaporators - and don't be anywhere near one when it does.
BTW - Oil filter is easy to change but there was a tradeoff- so here's where they buried the high pressure switch in the gen2s