Does the air flow also diminish in force through your vents when this happens?
To me, you described a frosty coil.

If so, it appears you are icing up on the evaporator which means the low pressure switch is running the too long. This system does not have a separate "deicing switch" to sense the coil that other car systems in the past had. This system monitors pressure only.
Yes, the car may have worked earlier, in the last year, but the humidity can change or the switch its self may have move from its factory setting after several cycles.

In setting, I mean two things. Its original set point or the differential spread may not be wide enough to allow defrosting to keep it from frosting up in your case.

There is an adjustment between the prongs on the switch to raise or lower the set point of the low side pressure. Just raising the pressure a few pounds raise the coils temperature several degrees.
Gage's should be used to observe any changes done to the switch.

The screw changes the spring tension inside in relation to the low side pressure and the movement of it is not much to create several pounds change. Probably less than a one-eighth turn, I think, clockwise will be plenty, if not too much as I remember! They can build this switch both ways to click off or on, with rise or fall of pressure. Good to have a set of gauges for this reason.

The differential is not an adjustment that can be altered. Replacing the switch is the only option. That can be done without loss of refrigerant as there is a schrader valve under the switch connection.

Good luck at dialing it in for your climate.
Phil