I just rebuilt my system, the orifice was covered in what looked like gray never seize. I cleaned the ac Evaporator and the AC condenser with acetone (thre's a small flow restirctor on condenser outlet), filling them as best i could with a small funnel, let it sit, blew them out with a high flow air line, then repeated about 3 times both directions until the rag i was blowing into was clean. I finally filled with denatured alcohol and blew that out. The flexible hoses i cleaned with the AC system cleaner NAPA reccomended, and i put in a NAPA reman AC compressor, dryer and new orifice. I have ice cold AC and its been fine for 6,000 miles so far. I also replaced the pressure switch on the dryer to go with the R134 pressures as well as all the o-rings. I vacuumed with a Harbor Freight vacuum pump for about 2 hours.