Of course, the reason you are converting to R134 is very likely the fact that your old system has leaked out its R12, so you know there IS a leak, somewhere. I agree that reusing the old hoses and seals works fine, but inspect the hoses first to see if there is any sign of leakage (an oily residue, usually near a fitting is the usual sign), and inspect the compressor shaft seal also. These only cost a few dollars, and anyone with the proper puller can inspect and replace it, and you don't need to "rebuild the compressor" unless it is making rude noises. If all of these look OK, then go ahead and re-use them. Dick Benjamin ----- Original Message ----- From: <72.lebaron@xxxxxxxxxxxxxx> . The most interesting bit of info relating to hoses and seals came > from the EPA's website. It seems that initially, when the EPA began > managing the migration away from Freon they recommended replacement of > hoses and seals that were previously in use on R12 systems. Now that > they've had enough years of field studies they've decided that the best > plan is to REUSE hoses and seals if possible. Apparently these items become > saturated with residue from R12 and it's lubricants and help increase a > hose or seal's resistance to leakage.