71 Lemans AC parts question
 

Put a new pro6ten compressor on my 71 Lemans Juiced it with the 134 oil & freon & headed out for the Hotrod Powertour. About an hour into the ride the ac quit performing as well as it had been. Checking under the hood my AC lines had about a 1/16th inch of ice on them. What else do I need to replace.. Is there a way to test the POA valve?

I'm not real familiar with that year, there should be a thermistor or capillary tube with a two wire hookup to cut out the compressor and prevent that from happening, The newer cars have a low pressure switch. Those are two beautiful cars.