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.

 

[pauleyman]

Every fitting I've seen you tighten it until the flanges meet. Is this the case for you?

 

[chrysler kid]

You will likely need to replace the ac o-rings on the expansion valve inside the dashboard, or replace the expansion valve entirely

 

[DogWhistle]

Just replaced our entire AC system last fall and went through leaks at the component joints, just like you.

It’s common knowledge in the GM car circles that aftermarket o-rings for many applications are slightly undersized compared to oem, so you have to make the separate step of ordering oem o-rings if you want to be free of leaks.

Due to the time constraints of needing to be on the road quickly, we couldn’t wait for Mitsu oem gaskets (assuming they were still available), but we were fortunate enough to have leftover o-rings from a previous AC system replacement and using those, we were able to finally get the system to seal.

What they *don’t* tell you about AC systems is that it may be 50-60psi when the system is running, but the pressure shoots to over 200psi when the compressor is turned off.

The system can test with a -30 vacuum for a long time and never strain it like those pressure spikes do.

Don’t reuse the o-rings. You may have to visit your local hardware store for slight beefier ones. Make sure the angle of the hose connector and the evaporator blocks are at the same angle rather than letting the bolt align them as you tighten.

 

[ty1975]

Every fitting I've seen you tighten it until the flanges meet. Is this the case for you?

They got maybe a paper thin gap, I didn’t want to crush the o-rings but after reading a little more it seems like on the block style fittings you should do them tighter than the hose to hose ones. So I’m going to snug them down and see

Just replaced our entire AC system last fall and went through leaks at the component joints, just like you.

It’s common knowledge in the GM car circles that aftermarket o-rings for many applications are slightly undersized compared to oem, so you have to make the separate step of ordering oem o-rings if you want to be free of leaks.

Due to the time constraints of needing to be on the road quickly, we couldn’t wait for Mitsu oem gaskets (assuming they were still available), but we were fortunate enough to have leftover o-rings from a previous AC system replacement and using those, we were able to finally get the system to seal.

What they *don’t* tell you about AC systems is that it may be 50-60psi when the system is running, but the pressure shoots to over 200psi when the compressor is turned off.

The system can test with a -30 vacuum for a long time and never strain it like those pressure spikes do.

Don’t reuse the o-rings. You may have to visit your local hardware store for slight beefier ones. Make sure the angle of the hose connector and the evaporator blocks are at the same angle rather than letting the bolt align them as you tighten.

Yeah the blocks are tricky, I dry fitted it and made sure it was good and straight. So I’m going to snug them down more and see if that’ll fix it. I’m wondering if that won’t seal it up

 

[DogWhistle]

We used a little lube on the seals, like you said you did, to encourage the seals to seat.

 

[ty1975]

You will likely need to replace the ac o-rings on the expansion valve inside the dashboard, or replace the expansion valve entirely

I didn’t realize the expansion valve was separate from the evaporator. I’ll have to do some digging on that. Is that a common fix for this?

I found the fastest way to evacuate the system..oops. Turns out you definitely can tighten them too tight. I didn’t feel like I tightened it that tight but I guess I did.

But these are the two o-rings from the last two attempts. It’s definitely pinching them and that’s the source of my leak. I’m betting it’s an alignment issue on that stupid block. Gotta get it just perfect when dry fitting I guess.

On the plus side at least that bolt broke long enough I should be able to get it out fairly easily.

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[chrysler kid]

I found the fastest way to evacuate the system..oops. Turns out you definitely can tighten them too tight. I didn’t feel like I tightened it that tight but I guess I did.

But these are the two o-rings from the last two attempts. It’s definitely pinching them and that’s the source of my leak. I’m betting it’s an alignment issue on that stupid block. Gotta get it just perfect when dry fitting I guess.

On the plus side at least that bolt broke long enough I should be able to get it out fairly easily.

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Wow

Are you using a generic o-ring kit or the specific o-ring kit for the car?

Were the old ones the same dimensions?

Maybe try hand tightening them slowly to fit

 

[DogWhistle]

I didn’t realize the expansion valve was separate from the evaporator. I’ll have to do some digging on that. Is that a common fix for this?

On many cars the expansion valve is a replaceable piece that can be done separately from the evap coil. However, our expansion valves are a 3 port model instead of a 2-port typical valve. One of the port tubes must be soldered into place. It’s not impossible, but don’t look to RA to have the right valve. It will be hard to find. *Gently* use compressed air to push old compressor oil out of the expansion evap coil — both tubes — in case it contains any contaminants that would harm your compressor.

Unless your AC didn’t work at all before the leaking seals, the accumulator valve is probably fine.

 

[pauleyman]

Why don't you try the torque specs for this

 

[chrysler kid]

On many cars the expansion valve is a replaceable piece that can be done separately from the evap coil. However, our expansion valves are a 3 port model instead of a 2-port typical valve. One of the port tubes must be soldered into place. It’s not impossible, but don’t look to RA to have the right valve. It will be hard to find. *Gently* use compressed air to push old compressor oil out of the expansion evap coil — both tubes — in case it contains any contaminants that would harm your compressor.

Unless your AC didn’t work at all before the leaking seals, the accumulator valve is probably fine.

Never seen them soldered.

In the first pic you can see the o-rings im speaking of. But your leak is obviously caused by those pinched orings to the core

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[1990TSIAWDTALON]

I have used THIS PRODUCT to clean out any old oil or contaminants, then blow it out with DRY compressed air and use the appropriate PAG oil to lube the o-rings before installation.

 

[ty1975]

Why don't you try the torque specs for this

Fine suggestion, thank you.

Wow

Are you using a generic o-ring kit or the specific o-ring kit for the car?

Were the old ones the same dimensions?

Maybe try hand tightening them slowly to fit

It is a generic but the same dimensions as the ones I took off. I wonder if the previous owner had the wrong sized ones to begin with though. I ran a thicker o ring on the suction tube and that looks like it took care of that leak. Now I just gotta ease that little o ring in and I think I’ll have it. The hand tighten idea is a good one.

 

[TerminalTalon]

I guess I would be a guru because I work on everything at it is the season.
OEM or bust for hobbyists.
Are you pulling a vacuum before charging the system?

Also just going off of somebody else’s depiction of what the right size o-ring looks like or if they just thought “these would work” doesn’t make both of the smaller(the left is cut and the right was clearly pinched). Eliminate the common factor of other peoples wrong opinions.
You can use the PAG oil to lubricate the o-rings which helps.

 

[ty1975]

Also just going off of somebody else’s depiction of what the right size o-ring looks like or if they just thought “these would work” doesn’t make both of the smaller(the left is cut and the right was clearly pinched). Eliminate the common factor of other peoples wrong opinions.
You can use the PAG oil to lubricate the o-rings which helps.

True, and yes I pull a vacuum before each time charging it up. Have been using the pag oil to lubricate them. I’m hoping I’ll be able to get that broken bolt pulled out tomorrow and try for a third time. Any tricks for dry fitting and aligning the blocks right? I think that’s a big part of the problem is that it’s cocked off to the side a bit and that’s why the o-rings keep getting chewed up

 

[1990TSIAWDTALON]

Have you tried test fitting with the oring inserted into the firewall fitting? It may reveal part of your problem. Just a suggestion as a test.

 

[TerminalTalon]

Let’s get some pictures of the hoses where they go into the evaporator. Just want to make sure they don’t have cracks or burrs. Just check the surfaces in general.
Get some OEM o-rings. There’s no need to get anything else unless the hoses aren’t manufactured to spec.
The fitment after seating the hose to the evaporator doesn’t matter. You just need a good seal. As long as the surfaces are mated the seal is the only thing that we care about.

 

[ty1975]

Have you tried test fitting with the oring inserted into the firewall fitting? It may reveal part of your problem. Just a suggestion as a test.

So I test fitted an o ring in there. I’m just not sure the ones that were in there are the right size. Also, full disclosure I scratched the block… don’t wanna talk about it. but it shouldn’t have any affect on sealing right? Also I did have a little bit of a scratch on the male side of the block that I smoothed down cared since it’s not on a sealing surface. I was mainly trying to make sure it wouldn’t hold it out as it was bolted down.

I’m not totally convinced this thing had the right size o rings to begin with. I fit a bigger o ring in the block and it seemed to fit.. there’s a pic of that. But it was loose on the hose. I guess there’s another argument for oem

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[ty1975]

This definitely looks a little kinked, and the end is a smidge messed up. That’d help line it up better to straighten that out, not sure if that pin can be replaced?

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[1990TSIAWDTALON]

I dont thnk that buggered up pin will effect sealing. You may need a THICKER oring so it seals in the block AND on the tube so whatever oring you can get to do both is good. The scratch on the block shouldn't hurt either. We just need the tubes to seal. A thicker oring may be a little harder to get in so lube it and the block both with PAG oil. Crossing fingers for you, it's been 100-105* here all week.

 

[chrysler kid]

Maybe try shrinking the line end with compressed air can upside down , slip the lube ring on it, then slide it in there

 

[ty1975]

I appreciate it guys, luckily this week has been rainy but other than that it’s been toasty. I tried a bigger o-ring, the one pictured sitting in the block but it leaked also. It doesn’t hug the hose tight though it just sits on the first shelf on the block. So I’m thinking the smaller one I tried previously would be best, I took a pic of it inside the block and you can tell it fits more snug, it’s actually slightly too big. The dimensions of that one are 8.8mmx1.9mm. Does anyone know what the oem size is?

Shrinking the tube with cold is a really interesting idea, I may just have to try that.

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[saturn345]

I have always pressured the system with compressed air with old r134a cheap Freon recharge hose and air fitting hose I put like 60-100 psi in system then spray fittings with soap water. Then if it check good then I evacuate system for half hour to make sure air all out and moisture out from shop compressor.
Helps most of the time.

 

[ty1975]

That’s what I’m doing is just compressed air, refrigerant is too expensive.

But I’m about at my whits end. I’ve switched out I don’t know how many o rings now, pressure side and suction side, I honestly don’t know which one is even leaking. Maybe both. And I can’t get it to seal. I’m about ready to epoxy the dang thing.

I have seen people post that they have used silicone on the mating surfaces. Is that a bad idea?

Any idea what size the oem ones are? I’m trying to find the size at least that way I could verify that it’s not a size issue. Cuz I’ll be super ticked if I get oem ones and they leak too or they get pinched.

 

[saturn345]

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