Rob Edwards

I'm going to re-o-ring all my A/C connections on my '90, and purchased the front and rear o-ring kit from 928SP. The o-ring kits are listed for 89-92 in front, and 87-95 in the rear. The compressor is a Nippondenso 10PA20C (Porsche P/N 928.126.113X) used on the '90 and '91 only. My understanding is that the kit does not include the compressor o-rings.

So- Any '90-91 owners that have worked on their compressors have any idea what size and/or # of o-rings there are at the hose connections on the compressor plate? The picture on the 928SP website shows two round o-rings and a trapezoidal-looking gasket that must be for the plate. I bought a $4 assortment of o-rings at Pep Boys and some ester oil, so maybe there'll be a fit. If no one knows, I'm diving in tonight and will report back.

touque

Rob - I had to replace my compressor o-rings on my '89 (which had a Denso compressor) and was able to go to O'reilly's and pick up the right ones (taking an old one as a test). They had the 'assortment' batch on the shelves which didn't have the right size, but when I asked if they had more, they pulled out this big case from the back which had every size imaginable. I was easily able to match it up and they were cheap too (something like $.75 each).

Bill Ball

You can get the complete o-ring kit here:
http://www.acsource.com/index.asp?Pa...ROD&ProdID=394

Shaft seal kit too:
http://www.acsource.com/index.asp?Pa...ROD&ProdID=100

I have the o-ring kit. The kit label describes the 3 large o-rings as 114x3mm. Is that the one?

Rob Edwards

Bill-

That's great info, thanks! I think the 114 mm o-rings must be the big case seals for the compressor, as that's more than 4 inches in diameter.

I'm actually specifically interested in the o-rings at the junction of the hoses and the plate on the top of the compressor. In this thread (linked below) , in post #3 Bob mentions these o-rings for what must be a 6E171 on his '89:

https://rennlist.com/forums/showthre...=A%2FC+o-rings


I'm sure it's easiest to just pull the darn compressor and see what's there, but the goal is not to rebuild the compressor, just to re-seal the system. Besides, I'm trying to be efficient- Since the wife's away, if I'm going to have to stop at Sears to buy a new 5-drawer tool chest to fit under my new workbench, I might as well save some gas and get the o-rings at Pep Boys at the same time.....

Bill Ball

Oh, the inlet and outlet o-rings...hold on

Bill Ball

Maybe this will help. Which part do you need?

borland

from the PET, here’s what’s prescribed for my 90’S4, in quantity, part number, size:

2 – 999.707.284.40 o-ring, 6.6x1.5mm
7 – 999.707.247.40 o-ring, 7.5x2mm
1 - 900.174.011.40 o-ring, low pressure switch
1 - 999.707.261.40 o-ring, 9x1.8mm
4 - 999.707.250.40 o-ring, 10.6x2mm
7 - 999.707.251.40 o-ring, 14x2mm
3 - 999.707.252.40 o-ring, 17x2mm


https://rennlist.com/forums/showthre...=a%2Fc+o-rings

dr bob

Rob--

Take the old ones and/or the manifold plate with you to the local parts place. You'll be out for something else anyway, even if it's just tacos. My then-local AC shop took care of the few o-rings that didn't come in the kit, including these. Since I was there getting the hoses rebuilt anyway, it wasn't an extra trip. Is that shop in MV/El Toro still there to do your hoses?

Rob Edwards

Bob-

I haven't looked for that shop yet. I went through the entire front A/C system last night, and pulled all the old o-rings and set 'em on a piece of paper, then lined up the new ones from DR's kit. Turns out (I think, at least) that both hose connections at the compressor are included in the kit (999.707.251.40), but the kit doesn't have enough o-rings if you replace the expansion valve and all four of its o-rings. I measured the OD and thickness of all the rings in the kit with a micrometer and will do a writeup when I finish up. My hoses look ok at the swaged fittings, so I'm going to chintz out on getting them rebuilt right now. Besides, removing the high side line from the compressor to the condensor involves removing the vertical metal bracket under the jumpstart terminal, which means removing the 8mm screw medial to/under the right headlight bucket. Ugh.

All told I spent about 8 hours last night completely removing the compressor and all the joints, though I bet half of that was de-gunking parts. The compressor's all shiny now, maybe it'll even function soon!

The battery is disconnected, and I need to remove the passenger seat to replace the rear o-rings. Of course, I stripped the hell out of the plastic gear in the passenger seat drive using a cordless drill. So tonight's plan is to pull the cables, get the seat out, and do the rear A/C o-rings and expansion valve. Any BTDT advice?

Bill Ball

Borland:

You have to be a genius with the PET. All I see for o-rings are 928 PNs except for the 944 ones for the compressor manifold. I looked over at the 944 and 911 for 89 (my model year) and the o-rings there have the same 928 PNs with only a few cryptic dimension notes (like NW8, NW 10, NW13). I'm using PET 5.

dr bob

Rob--

My expansion valves came with new o-rings, separate from those in the kit. Have you looked?

dr bob

Have the hoses rebuilt. You are almost there, so it seams kinda foolish to leave leaky bits in the car on purpose. The problem areas are not limited to the ends-- the hose itself is a sieve as far as the refrigeratnt is concerned. Some claim that the old mineral oil that's permeated the old hose actually helps it seal, but that only means the leakdown take a little longer. It still leaks.

On the seat drive-- even the hand crank is dangerous to those little soft nylon gears. Did the seat move at all with the drill? Did you say a dirty word? It's OK, the kids are gone.

There are some pieces of the rear air evap area that rattle. The fan blower and the plastic vents highlight the last. A recent post suggested using o-rings at the ends of the vents where they pivot on those little pins. I used some little felt pads, dyed black with a magic marker, on the minor baffles. The fan just takes a little support to cut most of the rattling when it's running.

Lubricate all yoir new o-rings with refrigerant oil as you assemble. Operating-theater clean is the order of the day of course, since any debris willl either keep an o-ring from seating well, or will foul an expansion valve. Edsel Murphy reminds us that anything that falls into the system will be downstream of the receiver/drier.


There's a parts-n-tech specs supplement for early S4 cars that lists all the o-rings and their locations, including a blow-up assembly diagram with all the hoses, lines and connections noted. That supplement is undoubtedly in Jim M's CD collection. I'm just looking on my 928 manuals shelf here in the office and don't see it, but it is around here someplace if you can't find it on the CD.

Bill Ball

One relatively cheap solution is to get one of these kits. Quite a pile of o-rings and very cheap, especially for the 89- kit.

90+:
http://www.ackits.com/merchant.mvc?S...ehiclespecific

89-
http://www.ackits.com/merchant.mvc?S...ehiclespecific

BUT, I can't say for sure they will cover all the needs yet. I have the 89- kit but haven't got enough of the o-rings dimensioned to say. The PET has a limited number of PN that repeat over and over.

Here is what I get from PET5 for my 89:

431.260.749.A
- high pressure switch (1)

900.174.011.40
- low pressure switch (1)

928.570.635.00
- rear air solenoid (2)

928.573.635.02 (aka NW10 on 911) - I matched these to 13.7 x 1.9 included in a HNBR o-ring kit from Kragens.
- both ends of high pressure hose from compressor to condenser (2)
- rear AC high side expansion valve to evaporator (1)

928.573.636.02 (aka NW8, aka 5/8" on 911) - WSM says drier is 7.5 x 2mm
- connecting tube to lower condenser (1)
- both sides of drier (2)
- output line from expansion valve (1)
- rear AC high pressure line - both ends (2)
- rear AC high pressure line to expansion valve(1)

928.573.637.02 (aka NW13 on 911) - I measured as 15 x 1.8mm
- high pressure line to expansion valve (1)
- hose to suction on compressor (larger of compressor fittings) (1)
- rear AC suction (larger) line - both ends (2)
- rear AC evaporator return to expansion valve (1)

928.573.637.03 - I measured as 17.8 x 1.8mm
- suction hose to low-pressure fill port (1)
- both couplings to fuel cooler (2)

944.126.935.00 - I measured as 19 x 2.5mm. This is for the ND 6E171 compressor
- Compressor manifold (4)

borland

Great job Bill.

For others considering this job. Those Porsche part numbers are for reference only. Because Porsche charges about $3 per o-ring, the cost to buy these o-rings from Porsche not reasonable.

I remember buying metric HNBR O-ring assortment from one of the online suppliers (ackits.com or acsource.com). That covered most of the o-rings, but I still had to buy a couple from the local Carquest parts store. I did also buy a couple o-rings from Porsche that I could get otherwise.

Always use the old o-rings to size the new replacements and you'll be sure to get the right ones installed.

Bill Ball

Borland:

I appreicate the compliment. I still don't understand how you got those dimensions from PET and I need to correlate the 999 PNs with the 928 ones I saw.