Quote: Originally Posted by mp3z24
after all, how do you know that the seals are still good in the compressor?
Reminds me of the time that I tried replacing the compressor, on my old car, with a used one. The thing leaked like a siv. One of the seals was shot.
The advice given looks pretty sound. As mentioned earlier, flushing is important when replacing a bad compressor to remove all of the junk from the system. Also, if you've had the system open for a while the pag oil will soak up moisture, so flushing out all of that moisture saturated oil is definitely a good thing. The evaporator and condensor can usually be be flushed. The drier (or accumulator) can't be flushed, so it'll need to be replaced. If any of the hoses have mufflers in them, either they'll need to be replaced, or have the mufflers removed. The rest of the hoses can be flushed. Be sure to remove the orfice tube (or expansion valve) prior to flushing. Don't flush the compressor with any kind of solvant.
As for the compressor, your mileage may vary. I don't know of any way to check the seals ahead of time, but there are a couple of things to try. The pully that the drive belt connects to should spin freely since the compresor clutch isn't engaged. Try grabbing a hold of the inner hub and turning it by hand. It'll require some effort, but should be do-able. If it won't budge, the compressor may be seized.
As for tools, you should buy a flush-gun and some flush solvant. If you plan on charging the system yourself, you'll also need a vacuum pump and a good set of gauges. If you choose to have a shop vacuum/charge the system for you, you should let the shop install the accumulator (or drier) and add the oil, as both will soak up moisture if left out in the open for any length of time.
Regardless of what you do, it pays to do as much research as possible. Even if you choose to take it into the shop, you'd be an informed customer and much less likely to get ripped off.
If you choose to do this yourself...well it isn't for the faint of heart, but if you do your homework and avoid taking shortcuts it can be done successfully by a do-it-yourselfer. A/C tools are exensive, but they'll come in handy when you need to use them again.
Here are a couple of message boards worth looking at:
Aircondition.Com
Ackits.com
Hope this helps.