2G What is the correct size O-ring for A/C discharge line?

[GSXRunner]

Hello,

I have a leaking A/C discharge line going to the condenser. The O-ring was badly chewed up so I don't know what the correct size is for it. I have tried several sizes that came in a Harbor Freight kit that looked like it should fit, but they still leaked. If I pull a vacuum on it, it will hold the vacuum forever, but when I charge it, it leaks. It kind of acts like a check valve; it seems that the O-ring isn't falling into the groove when I plug the line in. Does anyone know the correct size (diameter & thickness) for these O-rings? If not, does anyone have their system open so they can measure this with calipers?

Much appreciated!

 

[kchaazz]

So, youre saying you bought an AC oring kit from HF, and the correct oring isnt in there? I do know that there are two cross sections on these orings, and it sounds like you need the thicker of the two. Ive replaced every oring on my own 1G car, and just used a kit from the Advance Auto or Autozone, I dont remember which, and it worked fine when we hooked it to the machine. When you pulled it back apart, did it appear that the oring was being smashed at all or cut?

 

[GSXRunner]

So, youre saying you bought an AC oring kit from HF, and the correct oring isnt in there? I do know that there are two cross sections on these orings, and it sounds like you need the thicker of the two. Ive replaced every oring on my own 1G car, and just used a kit from the Advance Auto or Autozone, I dont remember which, and it worked fine when we hooked it to the machine. When you pulled it back apart, did it appear that the oring was being smashed at all or cut?

I have tried several O-rings. Some of them got squashed (obviously too big). I have tried maybe 5 or 6 sizes. It seems that the O-rings are either too big or too small. I think I also bought a kit from Autozone last year and tried without any luck. This is really frustrating, but I want to fix this as it is too expensive to to charging it once a month. It's getting to the point that I've going to use a skin coat of RTV sealant on the two flat surfaces that come together. This is not the kind of repair I typically make, but it's getting to this point. You said there are two cross sections. Do you mean that the O-rings are thicker for instance measured from top to bottom than they are from inside to outside? If that's the case, that would explain why the ones I'm using don't fall into the groove.

 

[kchaazz]

Yes, there is a thicker cross section, meaning the "cord" itself is bigger around. Usually, the kits have some orings with both cross sections. Id also look into the grooved side of the connection to see if there is any debri from the original oring still in there. If the one youre using is too thick, itll just deform and leave a leak path, and you could potentially damage the sealing surfaces when you put em together. If its too small, it just wont quite seal.

 

[GSXRunner]

So, youre saying you bought an AC oring kit from HF, and the correct oring isnt in there? I do know that there are two cross sections on these orings, and it sounds like you need the thicker of the two. Ive replaced every oring on my own 1G car, and just used a kit from the Advance Auto or Autozone, I dont remember which, and it worked fine when we hooked it to the machine. When you pulled it back apart, did it appear that the oring was being smashed at all or cut?

Yes, there is a thicker cross section, meaning the "cord" itself is bigger around. Usually, the kits have some orings with both cross sections. Id also look into the grooved side of the connection to see if there is any debri from the original oring still in there. If the one youre using is too thick, itll just deform and leave a leak path, and you could potentially damage the sealing surfaces when you put em together. If its too small, it just wont quite seal.

Maybe the sealing surfaces are already damaged? How could a rubber O-ring damage the sealing surface? I didn't see any debri caught in the groove. They have a kit on ebay specifically for my DSM. I'm thinking of buying this. Kind of expensive for just O-rings, but if it's going to save me hours of time, it may be worth it. It's too bad I don't know what the correct dimensions are because I could just buy the ones I need. I already have so many O-rings, yet apparently not the ones I need.

 

[kchaazz]

I wouldnt purchase the DSM kit, Id just hit the parts store for a few bucks and return to base. having an oring that is too large on the thing could actually damage the surface by causing the flange on the opposite side to warp- eveything has to go somewhere, and when youre tightening things down and the rubber cannot compress anymore, something else has to give.
If you look closely at the picture of the orings in the kit in your link, in the second row down, the 3 orings on the left are the larger cross section than the rest of em.

 

[GSXRunner]

I wouldnt purchase the DSM kit, Id just hit the parts store for a few bucks and return to base. having an oring that is too large on the thing could actually damage the surface by causing the flange on the opposite side to warp- eveything has to go somewhere, and when youre tightening things down and the rubber cannot compress anymore, something else has to give.

Yeah, but unless I know what size to buy, going to the store isn't going to help. I remember going to Autozone last year to fix this same problem. They only had a kit that had a handful of differnt size O-rings. I bought that and didn't have any luck.

 

[kchaazz]

Hmm. Do you have a 2G car then? Cause the generic kit worked fine on the two 1G cars I redid the AC on. Maybe you could try a different line off a parts car as theyre not too difficult to change since your system is empty. Only other thing Ill mention is I lubed all the orings with a tiny bit of liquid soap before putting the lines back together to help avoid damaging the new orings. Sorry youre having troubles, but at least you dont have to rip the car apart to change the thermal expansion valve, which is what Im into right now. Ironically, its the only part I didnt replace when redoing the ac orings and compressor as I wasnt aware it existed...

 

[GSXRunner]

Hmm. Do you have a 2G car then? Cause the generic kit worked fine on the two 1G cars I redid the AC on. Maybe you could try a different line off a parts car as theyre not too difficult to change since your system is empty. Only other thing Ill mention is I lubed all the orings with a tiny bit of liquid soap before putting the lines back together to help avoid damaging the new orings. Sorry youre having troubles, but at least you dont have to rip the car apart to change the thermal expansion valve, which is what Im into right now. Ironically, its the only part I didnt replace when redoing the ac orings and compressor as I wasnt aware it existed...

My car is a 2g. I used A/C oil when I changed the O-rings.

I wound up doing what I said I was going to do. I put RTV sealant on the two flat surfaces, waited 15 minutes for it to skin up and bolted it together. I left it alone for an hour, evacuated and gave it a small test charge. Well, it sealed......but I found out that it is leaking in other areas such as around the compressor. I have a can of that Cliplight super seal laying around that I never used because I don't believe in sealers, but it's starting to look more and more like a good idea.