A/C O-ring sizes

[Jeffrey S.]

Does anybody have or can tell me where to find a size chart for the o-rings used in the a/c system on my '69? I used to have a good listing but can't find it anywhere. Thanks for any help.
Jeff

[Edward J.]

Re: A/C O-ring sizes

Hi Jeff, The A/C O-rings have a dia. and there is also a thickness difference most of the time. if you still have the O-rings that you removed you can take them to a auto parts store they may have a bin with all the sizes you may need. or some times places like Harbor freight sells a container with a bunch of different sizes. and maybe even places like Auto Zone or discount auto parts places. They can be about 20 bucks for a container of the different sizes.

[Harry S.]

Re: A/C O-ring sizes

There must be sizes in the shop manual......

I just got a set of these for my 63.

http://www.ebay.com/itm/270pc-R134a-HNBR-R12-NBR-A-C-O-Ring-Assortment-Green-/261185028352?pt=LH_DefaultDomain_0&hash=item3ccfd74100#ht_3204wt_1257

A size chart.

http://www.prepol.com/PPE-Uploads/Oring_sizes_AS568.pdf

[Terry M.]

Re: A/C O-ring sizes

Please be aware that the O-rings in an AC system must be made from the proper material if they are to last any length of time. That material is different for different refrigerant gasses. I don't think a hardware store or (yea gads) Harbor Freight is the best place to purchase O-rings for AC use. A commercial HVAC shop would be my choice, and be sure you know what refrigerant is going to be used when you go there. If you have the used O-rings, bring them with you. A good HVAC counter person should be able to eye ball the sizes you need from seeing them on the counter.

I am not so sure measuring the diameter (not the outside diameter, but the cross section diameter) of the material in used O-rings will be accurate. My observation is that used O-rings are not circular in cross section, but the take on a flatness from being compressed.

[Larry M.]

Re: A/C O-ring sizes

Please be aware that the O-rings in an AC system must be made from the proper material if they are to last any length of time. That material is different for different refrigerant gasses. I don't think a hardware store or (yea gads) Harbor Freight is the best place to purchase O-rings for AC use. A commercial HVAC shop would be my choice, and be sure you know what refrigerant is going to be used when you go there. If you have the used O-rings, bring them with you. A good HVAC counter person should be able to eye ball the sizes you need from seeing them on the counter.

I am not so sure measuring the diameter (not the outside diameter, but the cross section diameter) of the material in used O-rings will be accurate. My observation is that used O-rings are not circular in cross section, but the take on a flatness from being compressed.

Agree with Terry. The o-ring material of construction is very critical to good performance and long life. Generally for R12 and R134a refrigerants you want HNBR rubber o-rings. They are typically color-coded green for identification.

I have always purchased o-ring kits for my car rather than trying to buy the o-rings individually. DR REBUILD has excellent kits available specific for each car/year. Another source is ackits at http://www.ackits.com

Generally, GM codes the o-rings to match the standard end fitting………….such as #6, #8, #10, and #12. A #6 is for 3/8 (or 6/16) inch line. Others are similar. There are also a few special o-rings for POA valve connections, etc. The kits I mentioned have them all.

Let me know if more info is required/needed.

Larry

[Jeffrey S.]

Re: A/C O-ring sizes

Thanks to all for your help. I think I will just bring the o-rings that are on the fittings now to my local auto parts guy and match them up. I took 3 there yesterday and got them at a cost of 25 cents each. I only need these at this time to get the new drier attached before I put the hood back on. The rest will be done next summer. This way I will get only those I need and not have an oversupply that I may never use. I just thought if I had a chart I could go in and get them all at once and be sure I am getting the right ones. This will work fine. Thanks again!
Jeff

[Harry S.]

Re: A/C O-ring sizes

Thanks to all for your help. I think I will just bring the o-rings that are on the fittings now to my local auto parts guy and match them up. I took 3 there yesterday and got them at a cost of 25 cents each. I only need these at this time to get the new drier attached before I put the hood back on. The rest will be done next summer. This way I will get only those I need and not have an oversupply that I may never use. I just thought if I had a chart I could go in and get them all at once and be sure I am getting the right ones. This will work fine. Thanks again!
Jeff

After you put the new drier on will you be charging the system? or will the system be open to the atmosphere. If you put a new or rebuilt drier on and leave the system open the drier will absorb moisture and will become useless.

[Jeffrey S.]

Re: A/C O-ring sizes

Harry,
Thanks for the warning. What I intended to do was to install the side of the drier to the condenser and use the supplied plastic "seals" on the other side until I charge the system next summer. This is an NOS drier that must be 20 years in the box with the plastic plugs on both sides. How can you tell if the drier is still good or not? When I shake it there is something inside that moves up and down. Does this in any way indicate condition?
Jeff

[Terry M.]

Re: A/C O-ring sizes

Jeff,
Does it sound like one solid piece moving or many smaller pieces moving?

One solid piece may be OK. Many smaller pieces is not good.

There is a bag of desiccant (moisture absorbing material) inside the accumulator/drier. If that bag has absorbed moisture over the years of storage the only way to know it AFAIK is to open it up and replace the bag. If the bag has deteriorated and the desiccant is loose it is definitely no good. You do not want those desiccant particles loose in your AC system.

[Harry S.]

Re: A/C O-ring sizes

I'd wait on installing the dryer till your ready to do the entire system.

If the drier is DOA, there are two companies that I know of that will restore yours. One is in Tampa (Classic Auto Air) the other is in Ft Worth (Old Air Products).

I'm sending mine to Ft, Worth in a few weeks.

[Jeffrey S.]

Re: A/C O-ring sizes

Terry,
The moving piece is one solid, heavy thing. I shook the one I took off and it sounds the same. Th plastic plugs have o-rings and were screwed in tightly. If these things had a shelf life then I would think they would be dated on the box with a "use by" date like milk.
Harry,
maybe I will take your advise and hold off installing it until later. It's just so much easier with the hood off and I really don't feel like removing it again later.
Jeff

[Terry M.]

Re: A/C O-ring sizes

Terry,
The moving piece is one solid, heavy thing. I shook the one I took off and it sounds the same. Th plastic plugs have o-rings and were screwed in tightly. If these things had a shelf life then I would think they would be dated on the box with a "use by" date like milk.
Harry,
maybe I will take your advise and hold off installing it until later. It's just so much easier with the hood off and I really don't feel like removing it again later.
Jeff

Jeff,
I know there is no use by date, but I doubt they were intended to survive 20 years on the shelf. I also know they are supposed to have O-rings and the plastic plugs seal against them. The real problem is that there is no way to tell for sure if those O-rings and plastic plugs have held up for the duration, short of an obvious visible defect.

Once you get the system completed hold the vacuum on it for 24 hours and warm the receiver/accumulator. We used an incandescent trouble light near the unit back when. Check after an hour or so for too much temperature at the receiver/accumulator. The black ones will get pretty hot from the light, so you may need a smaller bulb and/or greater distance. You don't want to burn up the bag inside. You want to warm the desiccant to drive off any moisture and then the vacuum will pull that moisture out of the system. At least that is the theory.

[Tom L.]

Re: A/C O-ring sizes

Has anyone used one of these kits for an a/c system? I need every o-ring, have no old ones to match up and apparrently there are no known measurements.

http://shop.advanceautoparts.com/webapp/wcs/stores/servlet/product_hnbr-o-ring-24-piece-kit-interdynamics_9220013-p?searchTerm=a%2Fc+o-rings#fragment-1

Also, as noted by others if the dessivcant is loose the drier is not worth the potential trouble. I once had the pleasure of removing all of that stuff from a commercial refrigeration system that included hundreds of feet of tubing, not fun.

If you're using a good vacuum pump that will pull down below 29" HG do as Terry said, heat the drier so it is well above 70 degrees and run the pump for a few days but check the oil in the pump every 12 hours or so. If it gets milky change the oil, that's water mixed in. If the oil stays clear there was likely little moisture in it.

Another method which is NOT recomended is to bake the drier in an overn. Back in the late 50's my fathers employer was "Frugal" he used to bake the driers and re-use them to save money. The one thing he over looked was that since oil travels through a refrigeration (and a/c) system there is oil in the driers. He learned that the hard way, the oil reached it's flash point and his shop burnt down.

[Larry M.]

Re: A/C O-ring sizes

Has anyone used one of these kits for an a/c system? I need every o-ring, have no old ones to match up and apparrently there are no known measurements.

http://shop.advanceautoparts.com/webapp/wcs/stores/servlet/product_hnbr-o-ring-24-piece-kit-interdynamics_9220013-p?searchTerm=a%2Fc+o-rings#fragment-1

Also, as noted by others if the dessivcant is loose the drier is not worth the potential trouble. I once had the pleasure of removing all of that stuff from a commercial refrigeration system that included hundreds of feet of tubing, not fun.

If you're using a good vacuum pump that will pull down below 29" HG do as Terry said, heat the drier so it is well above 70 degrees and run the pump for a few days but check the oil in the pump every 12 hours or so. If it gets milky change the oil, that's water mixed in. If the oil stays clear there was likely little moisture in it.

Another method which is NOT recomended is to bake the drier in an overn. Back in the late 50's my fathers employer was "Frugal" he used to bake the driers and re-use them to save money. The one thing he over looked was that since oil travels through a refrigeration (and a/c) system there is oil in the driers. He learned that the hard way, the oil reached it's flash point and his shop burnt down.

Tom:

See my post #5. DR Rebuild or ackits have vehicle specific kits. LICS also had them for the mid-years, so this is another source (1967 should be same/similar to the early C3s). The only "tricky" o-rings are around the POA valve small connections. AC DELCO had (or perhaps still has) a paper guide to HOSES AND FITTINGS that shows all the o-rings and various fittings for the older cars. I would "google" AC DELCO and AIR CONDITIONING HOSES AND FITTINGS GUIDE to see if this info pops up. I got my copy from their website about ten years ago. If you can't find, let me know and I can scan and send to you……..about 5 pages. However, the pages themselves are marked Pages 250-255, so you can see they came from a large manual/database of info.

Larry

[Larry M.]

Re: A/C O-ring sizes

Jeff,
I know there is no use by date, but I doubt they were intended to survive 20 years on the shelf. I also know they are supposed to have O-rings and the plastic plugs seal against them. The real problem is that there is no way to tell for sure if those O-rings and plastic plugs have held up for the duration, short of an obvious visible defect.

Once you get the system completed hold the vacuum on it for 24 hours and warm the receiver/accumulator. We used an incandescent trouble light near the unit back when. Check after an hour or so for too much temperature at the receiver/accumulator. The black ones will get pretty hot from the light, so you may need a smaller bulb and/or greater distance. You don't want to burn up the bag inside. You want to warm the desiccant to drive off any moisture and then the vacuum will pull that moisture out of the system. At least that is the theory.