Where can I get o-rings for my air conditioning system? The local o-ring supply house recommends neoprene for refrigerant systems, and doesn't carry metric sizes. Is neoprene the right material?

 

Hi Mark,

We have those O-rings in kits, for the front A/C system on your GT it is $14, for the Rear A/C it is $8

 

Any parts store in you area like Carquest will have them as well. Make certain to check out the expansion valves carefully.

Best of luck!

 

Smart people trust locally obtained replacement parts....But not so confident people like me try to buy from the Big Three when in doubt. I learned that on my first German hose....I shook my head in disbelief when I found out (the hard way) that one end of the OEM hose was larger than the other end. Big Three knows this.

I've had mixed results with O rings with specialized use. Some are of a material that promotes longer life than others under certain conditions. Since I don't know this stuff...I rely on the advice of someone who does. Someday, I'll learn...but in the mean time...I drag out the plastic and wait for the UPS truck.

Harvey

 

Come on!

You are talking about o-rings. If you can't take the orings out of the car and march down you your local high quality parts supplier, then I can't help you. It isn't excatly rocket science to figure out o-ring size. Here is how I would do it. Place the o-ring sizes on the counter that you took out and match them up to the size of the new ones. You can even use a copy of of PET or fische to get the exact size and just call them! I know that it sounds coplicated, but have faith and give it a try! You know that even Griffiths gets the o-ring sizes wrong in their parts kits and they are supposed to be experts! Trust yourself more than anyone else because you are doing the work and others don't care as much.

Good luck!

 

PET doesn't actually have the o-ring sizes. Neither does the WSM, as far as I can tell. I found Greg Klanderman's list of o-ring sizes, and most of them are odd sizes that puzzle the auto parts stores.

I bought a little bag of standard neoprene o-rings from Autozone, and it contained pretty close matches for most of the o-rings. I figure that as long as the inner diameter of the replacement is not larger than the inner diameter of the original, I'm in pretty good shape.

 

Just a reminder that neoprene o-rings aren't suitable for AC service. The current recommendation is a silicone ring. Look for the green or sometimes blue o-rings to make your work worthwhile.

NAPA stores have an assortment of suitable o-rings, if you need a local source. I spoke with DR about it when I did the R-134a conversion, and he was able to put together a complete set for me, as he mentions in his post. He also had a great deal on the drier and the expansion valves. The drier is a 'must replace' item, by the way.

I took the hoses to a local AC specialist shop, where they were easily able to replace the rubber sections with new barrier hose. When I needed a few specialty o-rings for something I missed (hose manifold connections to the compressor body), he was able to supply those for me too. Another resource.

HTH!

 

Dr Bob,
Can you post the contact info. for the hose shop that converted your
standard hoses to barrier type? Having a difficult time finding a quality
spcialist down behind the orange curtain.

Thanks!

 

Mark:

It so happens I just talked to griffiths[.com]. Their site is informative and they claim to know Pcars, including 928. I have not dealt w/them before. If you don't mind the low level abuse "So what do you want?" attitude on the phone, they are slightly cheaper. I'm told by someone other than Griffiths that some of these o-rings are now $10.00/ea. If anybody finds a good source, please pass it along.

 

From surfing the web, I got the definite impression that neoprene is the right material for A/C systems.

I called the o-rings I got "neoprene" because the counter guy at the Autozone called them that. They don't say "neoprene" on the package, are green, and are intended for A/C systems.

I'd rather figure it out myself and source parts locally than put up with griffiths's attitude.

 

The most commonly used o-ring is HNBR, or Hydrogenated NBR (Nitrile Butadiene Rubber). This rubber compound, usually colored green, is compatible with both R12 and R134a.

A good source of technical information is found at this manufacturer’s web site:

http://www.afmusa.com/

Probably due to a lack of technical details by auto manufacturers on a/c o-ring sizes, most a/c parts suppliers don’t sell o-rings by size, and have resorted to selling o-ring kits of the most common sizes.

The PET actually does specify o-ring sizes. For some part numbers listed without size, they can be found on the 911 series parts tables.

One problem I see with the PET is it actually specifies non-standard size o-rings, and it appears that Porsche increased the o-ring sizes when it converted to R134a in 1994. If you look at the tables in the above link for the various o-ring sizes, you’ll find that the 2 mm cross section metric o-rings are non-standard. I suspect that when a 7.5x2mm o-ring is specified, what is actually shipped is a 7.5x1.8mm size, which is the original size when the car was built for R12.

Now, 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

So, if you substitute a 1.8mm in the above list, I think you’ll be fine.

 

Is the 999.707.261.40 the temperature switch o-ring? If so, the 900.174.011.40 looks like the same size.

 

HNBR -- that's what the o-rings I got are made of. I wonder why the counter guy called them neoprene.

By the way, the 9X1.8 and the 6.6X1.5 were the only two sizes that didn't have close matches in the set of o-rings I bought.

 

A-M Air Conditioning in Cypress did mine a few years ago. They have a shop in the Mission Viejo area, at least that's what it said on their trucks. I don't live there any more so I can't say if the MV shop is still there. Time for the fingers to go walking? The Cypress guys do a lot of dealer hose fixes, and were quick, reasonable, and got the alignments on the end fitting exactly like the ones I took to them. Nice guys!


HTH!