Automotive AC troubleshooting 101 - help me get started?

[SC Maintenance]

A large leak from an intact O ring?
PAG oil is good enough, O rings come in standard sizes, any dull tool will work fine to remove the O ring, maybe a zip tie.
How did the soapy water indicate when sprayed there?
Is there dye there, or inside the joint?

It alarmed hard with my $22 leak detector. We won't discuss how I got to that point - I have up trying to find fittings for my air compressor to fit, but I could continue to go that route if I need to. But the leak is from this area.

No dye in the system - so the manual is off.

It would alarm loudest with the nozzle right under the circled area - in a space behind the pipe right by the joint block. If I moved to under the pulley (which is left in the picture) - nothing. If I moved to the high pressure joint which is right in this picture, nothing. I could actaully hear a leak coming from this area. There was very little pressure on the system. The vehicle was not running.

You think could be a cracked hose joint maybe? New hose still available from Nissan - $117 plus freight from my favorite online dealer. Would a compressor fail somewhere other than the shaft seal - seems like there is nothing there to fail other than this pipe?

 

[Mechanician]

It alarmed hard with my $22 leak detector. We won't discuss how I got to that point - I have up trying to find fittings for my air compressor to fit, but I could continue to go that route if I need to. But the leak is from this area.

No dye in the system - so the manual is off.

It would alarm loudest with the nozzle right under the circled area - in a space behind the pipe right by the joint block. If I moved to under the pulley (which is left in the picture) - nothing. If I moved to the high pressure joint which is right in this picture, nothing. I could actaully hear a leak coming from this area. There was very little pressure on the system. The vehicle was not running.

You think could be a cracked hose joint maybe? New hose still available from Nissan - $117 plus freight from my favorite online dealer. Would a compressor fail somewhere other than the shaft seal - seems like there is nothing there to fail other than this pipe?

View attachment 284155

Yeah I don't think it's an O ring - it may leak now that you've disturbed it - but slow. A tooth pick should work to remove it without causing any anxiety.
The problem with a sniffer - it's hard to pinpoint anything, especially with a large leak. The refrigerant is in too many places. And if you neighbor passes gas it may go off.
I would again recommend soapy water - it doesn't lie.
If you did take the hose off the other (upper) end now would be a good time to pour some dye into the hose, before reassembly there.

 

[Mechanician]

Look to see if there's anything that looks like this sticking out of the compressor.
Sometimes a pressure relief will let loose, and not seal back up.

 

[SC Maintenance]

Look to see if there's anything that looks like this sticking out of the compressor.
Sometimes a pressure relief will let loose, and not seal back up.

View attachment 284165

Not that I can see, but I can only see a small part.

I am pretty sure its in that area, my meter is like a geiger counter, and it clearly alarmed most right there. Maybe the weld holding the pipe to that block cracked. Or the compressor itself seems to have a stacked assembly right there, so maybe the compressor itself is leaking not the shaft seal? I guess I take that hose off and have a look tomorrow, see if I can find some o-rings locally also.

 

[Mechanician]

Looking online - it appears the pressure relief valve is on the high pressure hose itself, in the fitting where it attaches to to the compressor. silver in color.
Another thought: Have you tried turning the clutch by hand a few revolutions? Maybe the compressor went bang, and is cracked somewhere out of sight.
The size of the leak, and the fact you can hear it means something should be seen if a line was cracked that well.
Even if you temporarily reassemble it, and test it with just a couple of PSI, it should bubble at the source.

 

[SC Maintenance]

Looking online - it appears the pressure relief valve is on the high pressure hose itself, in the fitting where it attaches to to the compressor. silver in color.
Another thought: Have you tried turning the clutch by hand a few revolutions? Maybe the compressor went bang, and is cracked somewhere out of sight.
The size of the leak, and the fact you can hear it means something should be seen if a line was cracked that well.
Even if you temporarily reassemble it, and test it with just a couple of PSI, it should bubble at the source.

I will take it apart tomorrow and try to get a better look at everything. If I see nothing wrong I will re-assemble and see if I can make some bubbles.

I have no idea how I would try to turn the compressor by hand? Presumably I would need to engage the clutch with a jumper wire?

Honestly I am pretty happy I found it. If its at that location then a new compressor and 2 new hoses would be worst case scenario - unless there is a second leek somewhere.

 

[Mechanician]

I will take it apart tomorrow and try to get a better look at everything. If I see nothing wrong I will re-assemble and see if I can make some bubbles.

I have no idea how I would try to turn the compressor by hand? Presumably I would need to engage the clutch with a jumper wire?

Honestly I am pretty happy I found it. If its at that location then a new compressor and 2 new hoses would be worst case scenario - unless there is a second leek somewhere.

The plate on the front is what you would turn. Turn it clockwise and confirm is rotates smoothly.

Not positive this is what you have, (listed as OE) the three lugs sticking out the front would be what you turn.
The plate they're attached to is what the electromagnet draws against the belt pulley behind it.

 

[Nukeman7]

I believe you have found the leak and it is simply a bad o-ring. It is appears to me that the o-ring has shrunken/flattened where the o.d. is at or below the diameter of the pipe nipple in this photo.

Don't go chasing any other source(s) of the leak until you replace this o-ring and perform the 20 minute vacuum hold test. If it holds vacuum, you are golden...if not, continue to check for additional leaks. I'd just get the green o-ring multi-pack from your local Autozone/Advance Auto Parts/O'Reilly stores or see if your local NAPA will sell you a couple of loose o-rings of the correct size. You want the o-ring's o.d. to be slightly larger than the nipple's o.d. so it will fit snugly in the compressor orifice. As @Mechanician suggested, I'd just lubricate it with the PAG 46 oil you already have. Nylog blue is nice, but probably not necessary for this particular coupling. Think about it, Nissan did not use Nylog at the factory during initial assembly.

Also, I do NOT recommend replacing the hose(s) since that can likely induce additional leaks at the intact o-rings. When it comes to A/C work, just fix what is broken or you will risk compounding the problem.

p.s., that Elitech sniffer is the best $22 you will ever spend!

 

[mk378]

That o ring was cut during installation. Make sure to lubricate the o ring and it should be possible to push the fitting in by hand, then install the bolt. Don't force it together with the bolt.

 

[SC Maintenance]

I took the pipe out yesterday so I could inspect. Its intact but it very "square". It took virtually zero force to push the pipe / o-ring back into its seat. I believe that is at least one of the problems, I saw nothing wrong with the pipe. I have ordered new ones and need to get a new vacuum pump and will try again this weekend.

That o ring was cut during installation. Make sure to lubricate the o ring and it should be possible to push the fitting in by hand, then install the bolt. Don't force it together with the bolt.

The O-ring is 17 years old, so probably just age. Either way it needs to be replaced.

 

[Mechanician]

I took the pipe out yesterday so I could inspect. Its intact but it very "square". It took virtually zero force to push the pipe / o-ring back into its seat. I believe that is at least one of the problems, I saw nothing wrong with the pipe. I have ordered new ones and need to get a new vacuum pump and will try again this weekend.


The O-ring is 17 years old, so probably just age. Either way it needs to be replaced.

Yes an O ring can leak - but I can't recall ever seeing one go from sealing perfectly for many years, to a large leak suddenly.
Typically the daughter would have reported that the A/C wasn't as cold as it used to be, well before it was completely empty.
But I never say never.

 

[SC Maintenance]

Yes an O ring can leak - but I can't recall ever seeing one go from sealing perfectly for many years, to a large leak suddenly.
Typically the daughter would have reported that the A/C wasn't as cold as it used to be, well before it was completely empty.
But I never say never.

Well she reported it didn't work around the time this spring it would have first been needed, so she may not have noticed. She doesn't drive a lot - she just finished school. She is 23. It wouldn't be unlike her not to notice until it was kaput

I guess I replace the o-ring then move forward - if its still leaking we continue.

 

[Nukeman7]

Well she reported it didn't work around the time this spring it would have first been needed, so she may not have noticed. She doesn't drive a lot - she just finished school. She is 23. It wouldn't be unlike her not to notice until it was kaput

I have witnessed a complete loss of R-134a on a Honda Odyssey w/dual A/C units in 3-4 hours due to a bad o-ring. There was no obvious visible or audible indications of a leak, other than the Elitech detector alarming near the coupling.

I guess I replace the o-ring then move forward - if its still leaking we continue.

That is the most reasonable and cost effective strategy. You might want to get the free loaner vacuum pump from Autozone to conduct the initial leak test while you decide on which pump to buy. Or install the new o-ring now and recheck using your previous method with the sniffer.

 

[Mechanician]

Well she reported it didn't work around the time this spring it would have first been needed, so she may not have noticed. She doesn't drive a lot - she just finished school. She is 23. It wouldn't be unlike her not to notice until it was kaput

I guess I replace the o-ring then move forward - if its still leaking we continue.

Good plan.
Typically an O ring that's in such a well secured joint would not suddenly develop a large enough leak to become empty over a few months.
I would think if it were to develop a leak, it would have taken a few seasons to degrade that far, starting out small.
Unlike that old Ford system where the connections were held in place by a spring. They would look like a Christmas tree under a UV light.

 

[SC Maintenance]

Stumbling along...

So it wasn't that o-ring - or there was more than one leak. It was leaking from the high pressure line behind it - bubbles proven. That o-ring was still intact, and there were lots of bubbles. Again, I could see no failure in the pipe. I tried to take a picture but its buried beyond too much stuff.

So next problem.

The suction line I pulled off and measured with a set of plastic calipers - I didn't want to use anything metal. It appeared to be 17mm - which I supposed could also be 11/16 - 17.46mm. I have a giant set of o-rings I ordered from Jeff Bezos. Figuring its a Nissan I installed the 17x2.5mm, which seemed to fit well, both on the pipe and on installation.

However the high pressure hose measured about 11.5mm. No idea what that was. 10mm o-ring was definitely too small, and 12mm was way too big. a 7/16 (11.11mm) x 3/32 was very tight to get on but fit, and on installation felt to have about the right amount of pressure pushing the joints together.

So I have a feeling one of those sizes is wrong, I can't see an OEM mixing measures past about 1985. I looked online but I can't find a listing for a Nissan O-ring. I wonder if the dealer sells the proper ones out of the catalog?

 

[Nukeman7]

Stumbling along...

However the high pressure hose measured about 11.5mm. No idea what that was. 10mm o-ring was definitely too small, and 12mm was way too big. a 7/16 (11.11mm) x 3/32 was very tight to get on but fit, and on installation felt to have about the right amount of pressure pushing the joints together.

So I have a feeling one of those sizes is wrong, I can't see an OEM mixing measures past about 1985. I looked online but I can't find a listing for a Nissan O-ring. I wonder if the dealer sells the proper ones out of the catalog?

The o-ring for the high pressure rubber hose should be available from NISSAN dealership as Part No. 92472-N823A. Also available from Z1 OffRoad parts.

The o-ring for the low pressure suction hose is 92474-N823A, also available from Z1 OffRoad.

 

[SC Maintenance]

The o-ring for the high pressure rubber hose should be available from NISSAN dealership as Part No. 92472-N823A. Also available from Z1 OffRoad parts.

The o-ring for the low pressure suction hose is 92474-N823A, also available from Z1 OffRoad.

Cool, thanks. They do have them, and Z1 has them both. $8 for an o-ring makes me want to cry, but I think I am going that way anyway, easier than finding out in a month with an empty system.

Looks

 

[Mechanician]

Happy to see you have it sorted - Happy Fathers day.

 

[SC Maintenance]

Happy to see you have it sorted - Happy Fathers day.

Thank you. Could be problem 1 of many. Learning a lot!

Happy Fathers day to you also!

 

[Mechanician]

Thank you. Could be problem 1 of many. Learning a lot!

Happy Fathers day to you also!

Thank you.

I don't believe you've created any new problems with your approach, most likely the leak repair will be all you have.
Proper evacuation, new drier, I assume you didn't lose much oil since you didn't see any.
I suggest some preemptive dye while it's apart, and you should have it wrapped up.