89 supercoupe with major A.C. headaches.

[Jim Adams]

My A.C. compressor locked up and when I opened it up tons of black sute came out,,I figured this was the FordsBlack syndrome everyone talks about,,I replaced the compressor and retrofited it to 134a not to my suprise it stopped working about 3 days later,the liquid line(also the orifice line) had plugged up ,at this point I new I was in for a ride. I then replaced the accumulator Dryer the liqiud line another A.C. compressor then I flushed the condensor with mineral spirits and blew out the evaporator,,well today I evacuated the system for about 30 minutes to burn off any moisture from all my work and added one can of 134a then one 2oz can of freon with ester oil and oring conditioner and it started getting cold then when I was on my second can of 134a and was just about ready to check the pressure as Im sure it was aproaching 35 to 40 lbs,,the compressor locked up. Im thinking it was a fluke and I just happened to get a compressor that was on its way out,,I did flush the compressor with ester oil and then let it pump up with an air ratchet on the front bolt to blow out any residue and that worked ok,,,Am I missing something?