The unit is not suppose to freeze you out. It is a air conditioner. A humidity remover, not a dead meat keeper. Ha Ha. Think more like a florist cooler.

The low pressure switch is pulling down coil pressure to low for the humidity.

That switch may be adjustable by a tiny screw. I think it is between the connector prongs.

Adjust the low side pressure up about 4 to 5 pounds on cutin/cutout range. Cut out pressure should allow the coil up above 34 degrees for a defrost cycle. I allow about a 10 degree inside to outside the tubes, for a heat exchange rate on evaporators.

Check temperature/pressure relation chart for your refrigerant you are using.

If the spread is not enough then the switch spring is bad. I believe it can be swapped out without discharging the system. When the switch is screwed on it pushes open the valve port so the switch can sense the low side.

Cabin temperature for these cars are controlled by the fan speed or volume of recirculated air across the coil. If you use an outside air mix you will get more moisture.

If the unit contantly shuffles back and forth then the system is low on gas. Since you are getting plenty cold, that is not your problem.

Phil