I'm getting my AC reconnected on my 69 Coronet R/T. going to 134.

the shop is telling me my system keeps freezing up... I had installed a new compressor before taking it in and had them reconnect the discharge and suction hoses to avoid leaks being my fault. what i didn't realize was that there was no EPR valve in the remanufactured compressor. As I had read about so many folks pulling their EPR's when converting i figured this would not be an issue (I already returned my core long ago and left the EPR valve in it). there replacing the expansion valve and retrying... do i need the EPR valve? where can i get one? or do i need the thermostatic cycling switch from Classic Air? Can i install this after having it charged?

I'm likely running up quite a bill and may not be moving towards an operable system

It is tough to find shops in these parts that still know these systems well.

thanks