I have no way of knowing much until you evacuate, charge and check pressures and vent temp.
The r/d would not cause the system not to cool unless it were plugged up. It would be a good idea to replace it. Since you are flushing, you will be able to get the correct amount of oil in the system. Just because you saw very little oil does not mean that it was low. The oil is distributed and sometimes certain parts will be dry.