garyabc

So I have everything I need for the R12 to R134 air conditioning conversion on my '84 944 /1 NA. Not sure which oil to use.

The Porsche Technical Service Bulletin for A/C retrofit says to use 300 ml of "ND-Oil 8 Refrigerant Oil".

Should I use PAG 46 which is recommended for the Nippon Denso 6P' compressor with 134a?

Or, should I use the Ester 100 "specially formulated for retrofitting R-12 to R-134a and compatible with residual chlorine from R12..." ?

I plan to remove the compressor to drain the oil, blow everything out with air then use a flush kit. I don't plan to remove the evaporator or condenser separably. I'll use a new receiver/dryer.

Since the oil in not in an aerosol can and I don't have any specialized A/C sevice equipment (just gauges & a vacuum pump) I assume I just add the correct amount of oil through the input port, correct? but which oil?

Thanks for you help,
Gary

cruise98

Personally, I would flush the system like you suggest and use the Ester unless you change the rubber hoses. I have a 10+ year old Sanden on my car and used the Ester. Add the oil to the compressor before you mount it and after mounting it and connecting the hoses, be sure you turn the compressor by hand a couple of dozen times before turning it on.

garyabc

Good suggestion, Keith, Thanks. Hoses are quite expensive and 25 year old rubber is always a problem. Hope to get a chance to work on it tomorrow.

Andy Kay

Gary,

A few months ago, I was losing freon from the fitting by the driver side rear wheel. My mechanic found a guy who made new hoses and fittings to replace my 32 year old set up. The indy charged me $25 per hose and took about 20 minutes to make. You may want to give this a try. It worked for me.

John_AZ

cruise98 is correct for what you have decided to do.

300+-ml equals about 10oz of oil.

That would be for a bone dry system, perfectly flushed, new condensor.

You do not have that.

At most maybe 6 oz total of additional oil.

3 oz in the compressor, 1 in the receiver dryer, another in the condensor.
And if you were in a perfect world----1 oz just before the evaporator/expansion valve.

Too much oil will bog the system and kill the compressor. The compressor pushes gas--not oil. It will burn out.

If you wanted to be certain about what to do----search for Griffiths on the forum. He was an active member a few years ago. He has great advice----for you to do it right. He also has a web page www.griffiths.com

You should flush the condensor separately--easy. Oil settles at the bottom of the condensor and could block the freon.


Small "O" ring kit at AutoZone
Big "O" ring 134a conversion kit at Pelican:

http://www.pelicanparts.com/cgi-bin/...0Each%20%20%20

GL
John

m73m95

I replaced my compressor yesterday.

You will need 2 of the small o-ring kits from autozone. The compressor requires 4 of the big o-rings, and the small autozone kit only contains 2 of the big rings. The rest of the o-rings can be replaced out of the kit.

John_AZ

Correct.

2 for the hoses and 2 under the manifold-yes, you need to remove the hose manifold and change the "O" rings if you want to do it right.

John

m73m95

Actually there are 4 under the hose manifold.

I replaced 4 (large) o-rings under the hose manifold, 2 for the hoses (1 on each), and 2 more for the receiver drier.

John_AZ

Right again,
I had 2s on my mind.
Picture of a spare compressor with storage seal plates attached.

garyabc

I definitely would have added way too much oil. I will try to measure what I remove from the compressor and add a couple of additional ounces assuming this totals 5 or 6 oz. I'll go with the Ester 100 oil with uV dye.

Now that I see there is condenser access from the front of the car, I'll remove it to flush separately.

Have a kit of 200 A/C O-rings so I should be OK there. If I do need hoses, I'll check around for a fabricator, good suggestion.

Thanks for all the tips! Going outside to get started now. I'll post the results when I finish.

Gary

John_AZ

Just to be sure...
Your kit of 200 AC "O" rings is for the R134a ----GREEN "O" rings
and not the old R12 black...

GL
John

cruise98

Gary:

I have had limited success with the o-ring kits having the proper sizes for our cars. Metric does not seem to be taking root just yet. The prices on factory o-rings are ridiculous, but if you have them they will fit.

Just to confuse the R-134a o-ring issue further, i have seem them in blue and green. I think HNBR is the proper material regardless of color.

ideola

Is there a comprehensive writeup somewhere on exactly how to do this conversion, including proper evacuation? A lot of the writeups I've seen say something like "evacuate the system by properly boiling out the refrigerant". Okayyyyyy, how do I do that? Would like to see something that is comprehensive and thorough, points out all of the seals required, etc. In one place. Don't care if it's generic, but it would be even better if it were specific to our cars.

John_AZ

First, GaryABC, I forgot to mention----use no more than 24oz of R134a ====2 - 12 oz cans from WalMart $8.97 each. OUCH last year they were $6.79 a can. What happened to the Roll Back pricing?

Ideola,
One of the best guides I found on the Internet for a beginner to intermediate garage mechanic to understand the Basic Principles...
Written in great detail:

http://www.docsblocks.com/FAQ.asp

For problems specific to our cars I use the WSM on AC issues.

GL
John

ideola

John, thanks for that, will go straight to the bookmarks file for later perusal.