AC Compressor Noise

88911coupe · 08-06-2011, 08:04 AM

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.

hcoles · 08-06-2011, 08:14 AM

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.

88911coupe · 08-06-2011, 08:31 AM

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.

hcoles · 08-06-2011, 08:34 AM

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

wwest · wwest's Garage

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

hcoles · 08-06-2011, 02:15 PM

Quote:

Originally Posted by wwest

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.

88911coupe · 08-06-2011, 02:56 PM

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

cgarr · cgarr's Garage

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

88911coupe · 08-06-2011, 06:12 PM

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

glennspiegler · glennspiegler's Garage

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

billybek · billybek's Garage

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!

ededoad@hotmail · 08-07-2011, 06:18 AM

Jumping belt = over pressure/over service