More a/c help please

[Brandon Rogers]

Guys-
so the saga continues.  patient is '84 urquattro with 3B motor including the big 200 20V radiator fan. Stock urq a/c system otherwise - except it's R134 now - was converted 2 yrs prior to motor swap and it worked fine until the swap when I removed the big line.   Fan comes on Stage 2 when a/c "on" and high pressure switch "closes".  The system has sat idle for about 2 1/2 yrs since I did the motor swap.  I had removed the "big line" from the compressor through the middle of the engine bay and over to the firewall.  While removed, I securely plugged the hole in the compressor with a rubber grommet.  I also covered the open pipe end at the firewall with tin foil (multi layers) and secured it with a hose clamp - so the system should not have been exposed to much debris, if any.  My a/c guy is telling me the system pressure, I think he said is all over the place - whatever he said, he said it's likely due to a sticking/clogged/whatever Expansion Valve at the Evaporator. 

Anybody have experience with this?  If I drive it a bit and build some pressure what are the chances it will free up? 

Any tips on replacing this part?

As always - thanks guys-

Brandon