jacrouch,

I would find another shop. They don't have a clue about what they are doing. It is not necessary to charge the system to see if the compressor is bad, they can simply turn it by hand and then jump the low pressure switch and listen for the clutch to click.

Additionally they are ripping you off BIGTIME on R12. I just bought 30 pounds for $425. That's about $15 per pound. I would say that 300% markup might be a shade excessive.

You can easily reach down and turn the front plate of the compressor by hand with engine off and see if it will turn and if so does it turn smoothly only feeling the compression pulses as you turn, sort of like cranking a lawn mower by hand.

Don't let these people BS you like that. TN 124's $79 diag fee is more in line with the rest of the industry.

Good luck,