Speedtoys

Replacing with a new compressor, condenser, and drier here soon.

88 S4, dual AC.

How -much- oil should I put in the compressor and drier..I know I cant put it all in either one...right?

Bilal928S4

I think the rebuilt compressor already comes with the required amount of oil. At least it does for other cars.

ammonman

Page 87-103 of the WSM gives the following approximate distribution of the total oil in the system for particular components:

Compressor=40%
Evaporator=35%
Condenser=15%
Fluid Tank (dryer) and lines=10%

The WSM recommends pouring the necessary percentage of the total oil charge based on the component replaced directly into the new component. The total quantity of oil for a system with the 6E171 compressor is 260-300 c.c.

Hope this helps.

Mike

Bilal928S4

Jeff,
Who did you end up ordering the condenser from? The eBay guy said 3-4 weeks. I talked with American Condensers and they said 10 days as both of them have to manufacture them and do not have them in stock.

dprantl

R134a or R12?

Dan
'91 928GT S/C 475hp/460lb.ft

Speedtoys

The Ebay guy. But a few days ahead of your order it appears.

Speedtoys

134, sir.

Hilton

I just put it all in the compressor - and turn the compressor over by hand a few times to push oil through it.

Speedtoys

Wow. I figured it might hydro lock with it all in there.

fraggle

when I rebuilt mine I just had the system suck it in once I pulled it to empty. I know I wasn't exact but it's been working for awhile without an issue.

Lizard928

Can't hydro lock a AC compressor as it doesn't have a compression stroke. It's either sucking in, or pushing out.

I always put fresh fluid in the compressor and install.

dr bob

Hence the instruction to rotate the compressor a dozen or two times by hand before doing under engine power.

Planning to flush the evaporator too, and replace the hoses?


In the end, you'll drain the oil from the compressor into a measuring cup, and put back in what the system requires. As interesting as it might be to assumne that it has the right amount for your car, it would be about the same as assuming it has what's required for every car that it might fit. And it probably has enough for a couple, give or take.

I'm a fan of POE oil in the compressor, if for no other reason than it gives you an absolutely painless retreat path to R-12 should that desire come up sometime in the future. If the compressor is loaded with PAG (and most are...) then you'll be draining/flushing a few times with POE before you install anyway.


I converted my 928 to R-134 about 15 years ago with absolutely no regrets. I have needed to top the system up a few times since, thanks to the car sitting and bleeding out the shaft seal. If I drive it regularly and exercise the compressor for a fw minutes a month, no losses at all. Meanwhile, I acquired a cylinder of R-12 JIC with no cars left that use it. It will either be priceless one day, or an excuse to declare my garage a superfund clean-up site candidate.

Herman K

Dr Bob,

You have any details of all the items you changed when you converted to 134? I'm about to get my white project 1988 car running again and consider the make the conversion at this stage.

Thanks H

dr bob

Drier, ALL the o-rings, and the rubber parts of all the hoses. Expansion valves. I missed a couple o-rings under the manifold plates on the compressor so had to go back in the next day. Except for doing the pressure hose rubber section replacement in place, no serious issues. I spent the bext part of a day on the project. It was very early in my stewardship period so there was a bit of a learning curve. I had the Porsche parts technical something or other that showed all the system components, so I could see where there were o-ring seals. DR was just starting his parts biz, so I asked him to put together a care package of all the o-rings. The compressor manifold plate o-rings weren't on the list but were available locally from the place the rebuilt the hoses so no inconvenience.

I'm very happy with the results. The freeze switch is jumpered for use in our dry desert climate, and it will easily pull the center vent temps below 20º F on a 90º+ day at 1500 engine RPM. It will freeze fingers on the steering wheel. Needed performance in a black S4 in Los Angeles.

IcemanG17

your 928 has an AC compressor.......mine doesn't....or an airpump, but that might be a good idea