What operating pressure?

that depends on the type of condenser you have, but i would say it should probably not be running at all. If you are trying to charge the outdoor unit you need to simulate a higher condensing temperature to simulate a warmer day outside.

The reason for this is because if your condensing temperature is lower than your indoor ambient temperature then you will have refrigerant flashing off in the liquid line and through the metering device when it hits the warmer indoor temp. Most condensing units designed for operating in cold environments will have head pressure controls, flooding valves, or fan controls to drive the pressure up high enough so that it doesn't condense at a temperature below the indoor temperature. A low condensing temperature wil also contribute to a lower suction pressure which can result in freezing the coil and flooding the compressor. This can slug the compressor and also wash the oil out of the crnakcase.

If you don't do anything to drive up your head pressure outside then you would probably be running something around 100psi and the indoor evaporator depends on the indoor temperature and humidity.

Obviously, there is no simple answer to this question because you have not described the system or how it is controlled except to say it's central air and has R22. Ther are a lot of variables and controls for running AC in cold weather. Ther are times when an AC will need to be run inside even in cold weather, but there are also cold weather controls for the outdoor unit to prevent damage.

You need to provide a lot more information.

maximum operating pressure is the max pressure you should use as an operating pressure, the day-by-day pressure that this thing uses, whatever it is. Pressure limit is the max pressure you can apply before it breaks. Normally, you want to be well under that pressure to avoid applying excessive stresses to the thing. .

at 40 degrees it should not be operating at all.