I don't know it this was resolved- but over or under charged systems won't cool properly.

Put a cheap thermometer in the vent and measure the air temp with the fan on high cruzin down the highway. It should be 45 F or so. Ideally colder 35-45F would be reasonable on a sub 100F day. Above 50 and there is a problem.
If they did the conversion correctly- which it sounds like they did with new hoses etc.. I'd gues it is filled with PAG 150 oil.

M