a/c compressor

I need to change out my a/c compressor on my 95 blazer I have a shop that will flush the system and recharge as soon as I am done. Am I better going there first remove the freon and oil and then change the compressor or should I just change the compressor with the freon in it and then take it to them and have them flush it and fill it. I would like to change it and then take it into the shop. Am I dangering anything or do I have to worry about condensation, Any help would be great. What would you suggest.

Whenever the system is opened, the refrigerant will escape. Legally, a certified AC shop must reclaim the refrigerant BEFORE the system is opened.

Before flushing the system: Remove the old compressor, accumulator, and fixed orfice tube. When the flush is complete, install the proper amount of oil in the system and in the new compressor. Replace the accumulator, fixed orfice tube and compressor. Do not reuse the accumulator or fixed orfice tube. Evacuate the system to 29" Hg for a minimum of 1 hour before installing the refrigerant.

Your compressor, (HT6) has a common problem of leaking at the case joints. It's usually caused by improper installation. Very important to follow the shop manual procedures and torque specs when installing the new compressor.