Starting work on AC system and I am looking for the o-ring sizes, so I can buy new ones.

I have read on the Forum that the Fiero uses captive and non-captive type o-rings on the AC fittings. In starting to remove fittings, the only type that I have found are non-captive or standard o-rings. Since the AC system does not hold pressure, I am questioning if the o-rings were changed during a prior repair, and the new o-rings were the incorrect size.

The car is a 88 V6 with a HR-6 compressor.

[This message has been edited by spark1 (edited 08-28-2007).]

Spark1 - Reading from the chart , the smaller tube at the condenser is a 3/8 inch captive o-ring. When looking at web sites for info, the 3/8 inch or #6 captive has a cross section of 2.62 mm. The existing o-ring measured a cross section of 0.070 inches or about 1.78 mm like a standard o-ring.

What size o-ring do you recommend for the larger tube at the condenser ?
On the car, there was dirt sticking to the condenser by the two fittings (found the leak), so I want to be sure that the o-rings are replaced with the correct sizes.
Thanks for your help.

Please educate me here. What is the difference between captive and non-captive? How can I tell? TIA

quote Originally posted by StockGT: Starting work on AC system and I am looking for the o-ring sizes, so I can buy new ones. I have read on the Forum that the Fiero uses captive and non-captive type o-rings on the AC fittings. In starting to remove fittings, the only type that I have found are non-captive or standard o-rings. Since the AC system does not hold pressure, I am questioning if the o-rings were changed during a prior repair, and the new o-rings were the incorrect size. The car is a 88 V6 with a HR-6 compressor.

The system does hold pressure. What ever the tempture is, is what the pressure is. Oh I just reread what you wrote, Yes replace all the o-rings. Go on a website and find the part number of all the o-rings or buy a kit for your car or take all of them to a NoAutoPartsAvailable and they will sell you all you need. Just remember dont use refrigerant oil on the o-rings use dielectric greese or motor oil.

Spark1 I just saw your post.

[This message has been edited by Kekipi (edited 08-24-2007).]

quote Originally posted by Alex4mula: Please educate me here. What is the difference between captive and non-captive? How can I tell? TIA

I noticed a few paragraphs about "captured" o-rings in the Factory Service Manual. It did not give the locations on the Fiero. A fitting designed for a captured o-ring uses a groove in the tube to retain the o-ring. The "non-captured" or standard o-ring does not have the groove feature. In looking at the different o-rings for the same tube size, the captured o-ring is thicker or in o-ring talk has a larger cross-section diameter. Comparing two 3/8 inch or #6 o-rings, a capture type has a 2.62 mm cross-section, and the standard is 1.78 mm.

Two GM o-rings

[This message has been edited by StockGT (edited 08-25-2007).]

Oh, I see. Thanks! This should has helped a lot when I did the A/C in my SUV but too late. Hope I got them right as I compared the cross section as you mentioned. Thansk again.

quote Originally posted by StockGT: Spark1 - Reading from the chart , the smaller tube at the condenser is a 3/8 inch captive o-ring. When looking at web sites for info, the 3/8 inch or #6 captive has a cross section of 2.62 mm. The existing o-ring measured a cross section of 0.070 inches or about 1.78 mm like a standard o-ring. What size o-ring do you recommend for the larger tube at the condenser ? On the car, there was dirt sticking to the condenser by the two fittings (found the leak), so I want to be sure that the o-rings are replaced with the correct sizes. Thanks for your help.

I made the chart a few years ago when converting my 88 to R134a. There were a few errors and some obsolete numbers in the old chart so I fixed those and reposted with the changes.

On your other question:

quote Condenser Inlet - #8 Male insert 'O' ring Condenser Outlet - #6 "Special GMC" (11/32-16 threads) male 'O' ring

Info from a now dead link but I think it's correct. Here is some more info from the same source that might be helpful:

quote #6 Barrier Hose is 5/16" Inside Diameter #8 Barrier Hose is 13/32" Inside Diameter #10 Barrier Hose is 1/2" Inside Diameter #12 Barrier Hose is 5/8" Inside Diameter #6 Tubing is 3/8" Outside Diameter #8 Tubing is 1/2" Outside Diameter #10 Tubing is 5/8" Outside Diameter #12 Tubing is 3/4" Outside Diameter #6 Female 'O' ring fitting has 5/8-18 thread (3/4" Wrench) #8 Female 'O' ring fitting has 3/4-16 thread (7/8" Wrench) #10 Female 'O' ring fitting has 7/8-14 thread (1-1/16" Wrench) #12 Female 'O' ring fitting has 1-1/16-14 thread (1-1/4" Wrench) #6 "Special GMC" male 'O' ring has 11/32-16 threads (11/16 Wrench) #6 Male 'O' ring fitting has 5/8-18 thread (5/8" Wrench) #8 Male 'O' ring fitting has 3/4-16 thread (3/4" Wrench) #10 Male 'O' ring fitting has 7/8-14 thread (7/8" Wrench) #12 Male 'O' ring fitting has 1-1/16-14 thread (1-1/16" Wrench) #6 Male insert 'O' ring fitting has 5/8-18 thread (5/8" Wrench) #8 Male insert 'O' ring fitting has 3/4-16 thread (3/4" Wrench) #10 Male insert 'O' ring fitting has 7/8-14 thread (7/8" Wrench) #12 Male insert 'O' ring fitting has 1-1/16-14 thread (1-1/16" Wrench)

Another good source for A/C part numbers is the ACDelco Air Conditioning Parts Catalog There are two catalogs, one for 85 and older and another for 86 and newer. The part numbers are helpful for cross reference if you want to use (cheaper) generic parts.

edit: Also see: Hose & Fittings and O-Rings, Gaskets & Snaprings in the "Pictures/Illustration Guide" at the same URL.

[This message has been edited by spark1 (edited 11-08-2007).]