Resolved 2G - A/C leak that won’t go away

[ty1975]

Need some guidance from some A/C gurus. My car has a leak where the lines bolt to the evaporator at the firewall right behind the battery.

I put new o rings on, universal ones from the parts store. It held a vacuum so I threw a can of 134 in. Still leaking. Soap bubbles right at those joints.

So then I take them off again, and notice I knicked the small o ring, so I replace that. Pressurize the system, still getting soap bubbles. So the. I put a thicker o ring on the big hose, and pressure it again. No bubbles. 60psi, I’m thinking all is good. It holds that for 30 min. I vacuum it down, add 134 again, then my sniffer goes off at the same spot. And soap bubbles again. But noticeably slower this time at least.

My question is, I didn’t tighten the bolts very tight. From what I’ve read you don’t want to over tighten them. Is that accurate on these? Or should I tighten them more. I got to snug then gave it probably another half turn. I tried to do the basics also, make sure it’s super clean, no nicks, oil the o rings, etc.

How to get this to stop leaking? Is it a common spot on our cars? Thanks in advance.

 

[ty1975]

I never use silicone on ac hoses or fitting. If it ever got sucked into system. It can ruin your system.

Good point. I’m about to just braze this dang thing together. There isn’t supposed to be a gasket like this in there is there?

Also where would one find oem o-rings? I’ve searched the inter webs and haven’t found any. Do you to go to Mitsubishi?

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[ty1975]

K I went and got an hbnr o-ring assorted box at harbor freight, I know that’ll make the hardcore oem guys squirm, but for anyone dealing with this in the future that is an option. You get a ton more o-rings for 11$ than even the assorted pack at the parts store. They are standard sizes rather than metric so slightly different. I got one that was just ever so slightly thicker and so far holding 75 psi with no soap bubbles. Not going to get my hopes too high, gonna let it sit a while and see how she holds. At the least I have ruled out the suction hose being a problem. With the change in bubbles on this one that definitely tells me it’s the high pressure fitting leaking.

 

[1990TSIAWDTALON]

It all has to do with tube size and sealing of the inside and outside diameters for ac stuff. THAT stuff has to seal. The flat mating surface doesn't really have much to do with the equation other than keeping things SQUARE.
If you do conclude that if you use the right oring it will seal, post back and let us all know it worked or it didn't please.
We all want to help and to know.

 

[ty1975]

It all has to do with tube size and sealing of the inside and outside diameters for ac stuff. THAT stuff has to seal. The flat mating surface doesn't really have much to do with the equation other than keeping things SQUARE.
If you do conclude that if you use the right oring it will seal, post back and let us all know it worked or it didn't please.
We all want to help and to know.

Thank you, I appraise it. This forum is awesome for helping people out. It’s held 75 psi for over six hours, I think I can call that a win. I’m going to pull a good long vacuum and try it with some refrigerant.

I think it was the slightly different size o-ring partially, the other thing was getting the fitment right. I made sure the fitting came together perfectly. But I also did not tighten the bolt all the way, which I had done on the other attempts. My ultimate hypothesis is that the alignment pin was supposed to be keeping the block from sinking down too far. The end of the pin was a little boogered up so I think it would push the o-ring too far in between that and my over tightening it. I think the o-ring was hitting that ledge way inside and that’s what was pinching/tearing them. As it sits now there’s actually a paper thin gap between the aluminum blocks. So for anyone having issues I’m the future, there were my mistakes. And you can use the harbor freight specials. No guarantees on how long they’ll hold. I think the parts store pack would work also but you get a lot more with the harbor freight pack. Thanks everyone for the help, I’ll post back tomorrow and report on how it goes with the refrigerant.

 

[ty1975]

I’m seriously about to give up on this thing. It held 75 psi all night. I pull a vacuum for 45 min, add enough to kick on the compressor and take the sniffer over there and it goes wild. Sure enough I have soap bubbles too. My plan is to let it ride, maybe the pressure surged when adding it, I know the high side runs above 100 psi most temperatures. Maybe the rings need to seat? Maybe I’m just being hopeful. I’ll drive it today, if it’s still leaking I’ll tighten it more, to be fair it’s pretty loose. I can still see a paper thickness gap. I’ll try that next. That doesn’t work I’ll get some dynamite.

 

[ty1975]

Tightened it down, made it worse, now my attention is turning to the alignment pin. Are those replaceable?

 

[TerminalTalon]

Do you have pictures of the leak with everything together?

 

[ty1975]

Do you have pictures of the leak with everything together?

I finally got it to seal. I feel like doing victory laps. This was the last o-ring. It was definitely the wrong size. Too big.

Here’s what I learned on this whole debacle. I finally ended up taking that hard line off so I could inspect it really well. Everything looked great. So then I looked at the stock o-ring on the other end and matched that size. Which I thought was a little small to be honest.

But I lubed that crap out of everything with pag oil. Then I fit the block in place and finger tightened the bolt in super easy. And bolt actually seated very nicely. Then I undid it and pulled it apart to see how the o-ring looked. It was perfect. So I fit a new one on, same size. Lots of lube. And pressurized it. It held 75 psi for a full day. I just charged it up, no bubbles. Nice cold air.

So lessons learned: get the right size o-ring. Test fit and pull it apart to see how things look (dry fit). And lots of lube.

Thanks a bunch for the help everybody. Hopefully if people stumble on this in the future it’ll help them.

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[1990TSIAWDTALON]

We really appreciate the follow up and.....HIP HIP HURRAY for you and your cars A/C!