AC Compressor Noise
 

Did search and no help. Here's situation. Added add'l condenser with fan in wheel well last spring, recently decided to add ProCooler.
In the PC installation I decided to flush the rear condenser in engine lid, the new condenser in wheel well, and the long AC line going into the new PC. I used mineral spirits as a cleaner (maybe a screw up?).
Vacuumed down system and held fine for a couple of hours then refilled with Freeze 12 and added about 2-3 ozs of the universal compressor oil that supposedly works with R12 and R134 (Freeze 12 is 80% R134). I added it in the line just before the PC (another screw up?) I had to ballpark the amount of Freeze 12 to account for adding the PC AND an additional condenser. I decided to use 3 cans (36 oz.) as a starting point. AC was doing only OK but seemed to work much better after being driven around for a day or so. Saw additional 5-10 degree drop in vent temps.
So far so good, but I now notice the compressor is noticeably noisier. Not really a grinding...just louder. I used a stethoscope to listen and can't hear anything horrible going on inside. There was also a very low frequency rumble that seemed to go away after I tightened the ac belt, which I could see was quivering pretty badly. With the belt off I spun the compressor and it seemed to be smooth as glass.
So, any idea on how to tell if the compressor is going out or just being "noisy"? It's a Sanden SD 5 FWIW.

listening in, could be overfilled with liquid hitting the compressor, that is not good as far as I've heard here, there are all sorts of DIY ways/methods to get the AC system messed up, you might consider finding a AC good tech familiar with Porsches to check things out.

Thanks, I'm thinking it may be an oil issue as well. I probably should have purged the WHOLE system or all residual oil. If it can just get me through the next couple of months I may do that when things cool down. The compressor is about 12 years old so maybe it needs to be replaced anyway.
Thanks for the suggestion.

sounds like you may have purchased the fender condenser from Griffiths, call and they will give you good advice

Probably need to add the hi/lo pressure sensor switch.

I have a generic question re. switch or switches on one of the other threads. I'll probably be faulted for over thinking.

Pressure 25-30/275-300 so far. Could high or low pressure cause noise?

That high side is pretty high. What you need to do is find out how much oil and 134a the system holds then flush it out completely, put in a new filter/dryer and expansion valve, add oil to the compressor, seal it up and vac it down then charge it. If your converting to 134a use about 85% or you will blow it up. Here is a conversion tech bulletin on how I did my Sanden on my VW. Pretty interesting.

http://faculty.ccp.edu/faculty/dreed/Campingart/vanagon/vwretrofit.pdf

Ambient temps were over 100 so may be "okay"...

Griff won't like it when he hears u added a procooler. He does have a very specific chart that tells u to charge on a hot day, and what the high side should be for the outside temp. u should not wait on this, if overcharged u will blow the compressor. If u do there will be more debri to clean out of system before replacing compressor, dryer, doing a leak test, and recharging if there r no leaks Good luck, Glenn

Not sure what oil you used but changing from a mineral oil to a POE oil will make most compressors sound noisier.
When you performed a standing vacuum test, did you restart the vacuum pump with a clean oil charge to try to minimize any non condensables that may have creeped in at that time?
Did you use a micron gauge of some sort to determine that the vacuum was holding?
My SC only takes 39 oz R12 from empty. You have some extra components that would require a larger refrigerant charge and I don't know the increase/decrease of volume for Freeze12.
Edit: I see you have 36 oz Freeze 12 total.... I have only one coffee in the system and thought you had 3 x 36 oz!

Jumping belt = over pressure/over service