If I were to build an air conditioner from scratch, I would design it around a certain capacity and a certain ambient. You balance out the cooling coil and the compressor and come up with certain evaporating and condensing pressures.

You look at the refrigerant pressure drop as it goes through the circuitting of the condenser coil, you subtract pressure drops of filter dryers, sight glasses etc in the liquid line, and you have less than the condensing pressure but more than the suction pressure.

Downstream of the TX valve there is the pressure drop of the distributor, the distributer tubes and even the evaoprator coil itself.

When you start subtracting all these in line pressure losses from the condensing pressure, and then subtract the evaporating pressure you are left with the pressure the TX valve has to work with.

The TX valve must be capable of passing enough refrigerant flow based on this pressure differential.

When there are no abnormal restrictions in the system, then over charging is just going to raise all the pressures.

Suction pressure/temperature will go up, head pressure temperature will go up.

I can't see the overcharge causing the freeze up.