A/C: rediculously small leak

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clutchdust

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Ok, about 1.5 years ago I fixed the AC system in the c5. The compressor ate itself so I got a new one with all the trimmings from Rock Auto. New o-rings and take out condenser from a CF member. Pulled a vacuum and it held, or so it appeared, 29" on my gauge for an hour. So I thought, "cool, good seal, so I charge it up and I should be fine."
Sure enough, all summer long it blew ice. Then it got cold so it didn't get turned on for 5-6 months. We took it out the other day and it was the first hot day we've had since last year. We turn on the AC and get blast furnace air. WTF?
When we got home I put my gauges on it and it had 40psi on both sides, and the compressor would only kick for about 2-3 seconds before shutting down. I cracked a line and all I got was hot air... no refrigerant.
When I put the new system in, I used oil with dye in it so I broke out the goggles and UV light but there is no sign of a leak anywhere. Now I'm mystified. I pull a vacuum again and sure enough, it appears to hold 28" for an hour. Since we're not driving the car regularly I just left my gauges hooked up to see what it would do. You believe this shit? But that thing lost 4" since freakin' Sunday! Less than 1" a day, and I can't prove that the loss isn't just a bad seal somewhere on my gauge set.
As best as I can figure a seal somewhere contracts when it gets cold and my gas just seeps out, so slowly in fact that it doesn't even leave a snail trail of dye. Can't explain it any other way.
Thoughts?
 
clutchdust said:
Ok, about 1.5 years ago I fixed the AC system in the c5. The compressor ate itself so I got a new one with all the trimmings from Rock Auto. New o-rings and take out condenser from a CF member. Pulled a vacuum and it held, or so it appeared, 29" on my gauge for an hour. So I thought, "cool, good seal, so I charge it up and I should be fine."
Sure enough, all summer long it blew ice. Then it got cold so it didn't get turned on for 5-6 months. We took it out the other day and it was the first hot day we've had since last year. We turn on the AC and get blast furnace air. WTF?
When we got home I put my gauges on it and it had 40psi on both sides, and the compressor would only kick for about 2-3 seconds before shutting down. I cracked a line and all I got was hot air... no refrigerant.
When I put the new system in, I used oil with dye in it so I broke out the goggles and UV light but there is no sign of a leak anywhere. Now I'm mystified. I pull a vacuum again and sure enough, it appears to hold 28" for an hour. Since we're not driving the car regularly I just left my gauges hooked up to see what it would do. You believe this shit? But that thing lost 4" since freakin' Sunday! Less than 1" a day, and I can't prove that the loss isn't just a bad seal somewhere on my gauge set.
As best as I can figure a seal somewhere contracts when it gets cold and my gas just seeps out, so slowly in fact that it doesn't even leave a snail trail of dye. Can't explain it any other way.
Thoughts?
Click to expand...

Evap core?
 
Exactly where I was going. Evap core. I've got a buddy in KC with a C4- I think he's on his 3rd or 4th one. The easy way to find it is with a sniffer.
 
Man, I do not even want to think about that. If it doesn't get any bigger, I'll just invest in $20 worth of R134 every spring.
I need to get a sniffer but those are a bit on the expensive side and I just can't justify it for as little as I would use it.
 
pull a vacuum again and recharge, Walmart has the cheapest R134 ... add stop leak, on a small leak like this it actually works - used this stuff on my Z28 and it fixed a small leak, this "fix" lasted over two years until I sold the car .... worth a shot.... I am suspecting the evaporator and that's a lot of work ....
 
I hate the idea of that stop-leak shit. It just goes against everything I believe about doing a job right. But if it is the evap core, I may fore go my hesitation in this instance.
 
clutchdust said:
Ok, about 1.5 years ago I fixed the AC system in the c5. The compressor ate itself so I got a new one with all the trimmings from Rock Auto. New o-rings and take out condenser from a CF member. Pulled a vacuum and it held, or so it appeared, 29" on my gauge for an hour. So I thought, "cool, good seal, so I charge it up and I should be fine."
Sure enough, all summer long it blew ice. Then it got cold so it didn't get turned on for 5-6 months. We took it out the other day and it was the first hot day we've had since last year. We turn on the AC and get blast furnace air. WTF?
When we got home I put my gauges on it and it had 40psi on both sides, and the compressor would only kick for about 2-3 seconds before shutting down. I cracked a line and all I got was hot air... no refrigerant.
When I put the new system in, I used oil with dye in it so I broke out the goggles and UV light but there is no sign of a leak anywhere. Now I'm mystified. I pull a vacuum again and sure enough, it appears to hold 28" for an hour. Since we're not driving the car regularly I just left my gauges hooked up to see what it would do. You believe this shit? But that thing lost 4" since freakin' Sunday! Less than 1" a day, and I can't prove that the loss isn't just a bad seal somewhere on my gauge set.
As best as I can figure a seal somewhere contracts when it gets cold and my gas just seeps out, so slowly in fact that it doesn't even leave a snail trail of dye. Can't explain it any other way.
Thoughts?
Click to expand...

That is why you never let a/c systems sit for long periods of time. I run my 97 camaros at least once a week for 30 minutes and it has never needed charging or nothing at 140k miles. Still blows ice cold like it did when it was new.
 
JeffP1167 said:
That is why you never let a/c systems sit for long periods of time. I run my 97 camaros at least once a week for 30 minutes and it has never needed charging or nothing at 140k miles. Still blows ice cold like it did when it was new.
Click to expand...

That is an excellent practice to keep that compressor seal in good shape.:1st:
 
Looks like I might have found my leak. I shot another can of gas in the system and it only lasted about a month. Broke out the black light and UV glasses and I saw fine splatter down at the compressor where the pressure hoses bolt to it. Pulled the block off and checked my seals, didn't see any damage and the rubber was still flexible. Kind of puzzling. Put new seals in, pulled a vacuum and recharged the system. We'll see.
 
clutchdust said:
Looks like I might have found my leak. I shot another can of gas in the system and it only lasted about a month. Broke out the black light and UV glasses and I saw fine splatter down at the compressor where the pressure hoses bolt to it. Pulled the block off and checked my seals, didn't see any damage and the rubber was still flexible. Kind of puzzling. Put new seals in, pulled a vacuum and recharged the system. We'll see.
Click to expand...

That's all it takes.
 
Yeah, but wonder why they leaked in the first place. Those seals were under two years old, absolutely no reason for them to fail. I was thinking it was possible for there to be something trapped between the seal and the surface but it blew cold the entire summer after I first did the job. Needless to say, I am puzzled.
 
Did you oil (with the correct stuff) the new rings? Every one I've ever had apart I oil the crap out of the fittings and o-rings- to the point they're hard to hold on to.
 
rumor I heard is that the R134a gas cannot leak past mineral oil.... so the oil in the O-ring groove would act like sealant.... no idea if this is true... when I installed the new AC on my Mustang I did not lube the O-rings and it's fine....
 
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