Volvo: 1999 Volvo S70 AC, chemical incompatibility, volvo s70

Question
Ray,

I recently got a black S70 for my kid. Now that I am almost done with fixing all the problems with its suspension, and other small items time to fix AC.
AC clutch does not engage when I turn AC on and there is very little pressure in the system. So I assumed that there is a leak somewhere. A mechanic at a dealership took the belt of and told me that AC compressor possibly generates some intermittent squeaking noise and need to be replaced. It is not clear to me why I hear the noise only when the car is in drive (not moving) but not in neutral. (Actually that mechanic lost credibility for trying to sell some other part I did not need.)

I am looking for your corrections/suggestions to my action plan. Here is what I was planning  to do.

1) Charge the system with  a can of  134A with dye in it and check if the system works and if there are any leaks.
2) If there are leaks I am not sure if I should try to use another can with a sealant in it. I do not know what the sealant is and if it could produce any problems  due to chemical incompatibility with the system components later. I would rely on your suggestion here.
3) If compressor needs to be replaced I’d take it to a mechanic, unless it is a simple job. How complex is that? Two bolts and two fittings or there is more to this?

Also do you have any suggestions about where to get an inexpensive AC compressor, are there any shops that specialize if rebuilding existing compressors?

And a couple of last questions:
What repair manual could you recommend that you prefer for 1999 S70?
Are there any common/frequent problems with AC on these cars that I should be aware of?

Thanks for your help

Regards,
Dmitri


Answer
Dmitri,
One can of Freon may tell you if the A/C works, but the system holds 1.63 lbs. A full charge is the only way to fully test the system for cooling. Noise maybe heard until the system is fully charged. When the freon leaks out it also takes small amounts of oil. So also add about two oz. of refrigerant oil. You can try to find a used compressor or buy new. I have not had any good luck with rebuilt units.
There are Haynes and Mitchell manuals, but the factory ones are the best. Sealant in the system may render other problems, I would avoid them.
I usually drop the subframe slightly to get clearance to remove the compressor, so you need support for the top of the engine as you will loosen the lower mounts.