Zero10

So, after fixing my broken CV shafts, I decided it was time to tackle the A/C.
Mistake.
Previously, it had a R134A retrofit performed by some little shop in TN. After replacing the leaky adapter fittings they installed, I thought I had my leaks fixed. Previously the system would hold enough of a charge for the compressor to kick on for 5-6 days, and it was very obvious that the refrigerant was leaking from the low side fitting (prior to replacement, last summer). So, this year I changed the fittings, and re-filled the system. I got a whole 3 days out of it before the compressor would no longer engage
I can't find any leaks anywhere. This has me stumped. No wetness at any connections, any hose ends, anywhere on the condensor (that I can see), etc.

So, I am trying to decide what the best way to find the leak is. It is possible that it is leaking somewhere that I cannot access, so I am debating between buying a sniffer, or a UV leak detection kit.
The sniffer would let me check the evaporator without removing all of the cowling, and possibly the same with the condensor, but isn't as easy to find the exact location of the leak with.
Seems like used sniffers go for ~$50 on ebay all the time, so price isn't a big deal.
Does anybody have experience with either leak detection method, and can they offer any advice on finding my leak?

austin944

I have a TIF leak detector, it looks like this:
http://www.sjdiscounttools.com/tif5750a.html

It found a leak in the evaporator of my friend's NSX. We just stuck it near the dashboard vents and down near the floorboards and it went off like crazy. He wasn't at all happy though since he had to tear the dash apart.

Aquadave

UV Leak Detection Kit. Might be cheaper to go to a shop and let them put the dye in your system, because they already have the tools/dye...but then you woouldnt get to creep around your engine bay pretending your on CSI examining a crime scene with an ultraviolet light and those cool yelloworange glasses!

nickg

you can get r134 with dye in it alreadcy. I use that, just charged up my cabby yesterday. it lasts about a year.

Zero10

Interesting. I like the leak detection dye since it is very precise, and I have a few UV lights, but I am worried it may leak somewhere that I cannot find it.
For sniffers, are there any brands/models that are better than others?
I am using duracool, which is a hydrocarbon refrigerant. I think that all R12 leak detectors will work with it?....

austin944

The instructions on the TIF say it will detect all halogenated (contains Chlorine or Flourine) refrigerants. I don't see hydrocarbon refrigerants explicitly listed in the instructions. It might not detect duracool.

Actually are you sure the UV leak detection will work with duracool?

Matt H

Uv detection is not precise. It is pressurized so as it spits it out it could be all over the place. Additionally, if the leak is internal you will have dye all over everything and it is NOT invisible dye, it is quite yellow.

Get a good sniffer. There are loads to choose from. I suspect you probably have an evaporator leak.
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Zero10

UV leak detection will work with anything. It's a black light reactive dye.
I think I'll buy a sniffer. Cost is ~$100, but it seems like a worthwhile investment, since I also have 2 friends with broken A/C.

I sure hope it's not the evaporator. I'd rather it was the expansion valve, or one of the O-rings....

Matt H

Zero, if you need help let me know. I think I have installed more than 400 AC systems in autos and I dont think I could count the number of repairs I have done.
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Zero10

Oh I need help, but not just yet. I have ordered a sniffer and it should take ~ 1 week to get here.
I seriously can't find the leak anywhere, and if the evaporator itself has a hole in it, then I think I will just give up. I am not going to remove the whole dashboard just to fix it. That said, I seriously doubt that there is a hole in the evaporator. I suspect the condensor is the problem. Duracool has a powerful odor of horse crap. If the evaporator was leaking I would probably smell it.
Right now I have replaced the low side fitting, re-fitted the middle part of the schrader valves into the original fittings, then used pass-through fittings in place of the old retrofit fittings.
I am using Duracool since it is readily available, and cheap. I plan to find all of the leaks before I make the switch back to R134A. If I can get it to hold a charge for a month, then that is good enough for me.
I have a couple friends who would like their A/C fixed, and by the time I have mine and theirs going, I should be an expert as well, lol.
I would appreciate any help you can give on the trek to get working A/C.

marky522

Just some info for you. If you want to finish this off right, if this was once a r-13 system, and the reciever/dryer wasnt replaced that will need to be replaced, since the system has been open to the atmospere the dessicant bag insde will be saturated, when you recharge the system, you need to place the system under a vacuum long enough to boil out the remaining moisture. The reason i bring this up is because if you dont get all the old oil out, and all the moisture out it creates an acid inside the system. If you follow these steps once you have the leaks fixed you will have a system tha blows ice cold. If you want it a little cooler splurge for the r-13, it will get you cooler A/C and works better at idle.

HTH.

Mark

Pauerman

Matt,

Have you ever tried Freeze 12 in the systems you've worked on?

Vic

marky522

Matt can comment also, but i'll tell you what i know, depending on the state you live in a blend like freeze 12 may not be legal. Another issue is if you ever take your car in for service most people will not touch a system with a blend.. Reason being you have two seperate systems, one for 134a and one for r-13, you cant use either of the evac systems or you will contaminate them, so its a pain to evac the system.

Mark

Zero10

FWIW, it's R12, and R134a
I am not familliar with R13.
Duracool blows just as cold as R12. When the A/C is working, it cycles on the freeze-up switch, so it works very well.
Freeze 12 is legal here, so is Duracool. All refrigerants are legal, except we are technically not allowed to fill a R12 system without certification. That doesn't stop a lot of people, but I agree with the ban on R12, and will not use it myself.
Receiver/dryer is original, the previous shop who did the conversion did not replace it. Shame on them. Once I have found the leaks I will replace it.
I also plan to remove the compressor and condensor and manually drain all of the oil from both pieces.
From there I know that you need to draw a vacuum on the entire system to remove all moisture, but at this altitude the best we can do is ~25" Hg.
I have not decided for certain, but here is how the refrigerant choice boils down.
Red Tek - says to KEEP AIR IN THE SYSTEM or else an overcharge will result.....
My 86 was filled with Red Tek, and they vacuumed the system before filling with a weighed charge. It was either under/over filled or else Red Tek is just crap, because it never cooled very well at all - Off my list!

Duracool - smells like horse crap, works wonderfully, and is cheap - seems good so far!

Freeze 12 - not locally available, but I have read many good reviews of it.

R134A - In my other car, and all of my family's cars and it works very well. However those systems are designed for R134A, and mine is not.

I think this means that I will use duracool in my A/C unless it turns out to be the compressor which is leaking, at which point I will buy the griffiths kit and fill with R134A.

Matt H

Vic, used Freeze 12 twice both times the compressor failed. Never used it again.

If you have access to R-12 use it, I have yet to find a suitable replacement that worked as well. Converting a 944 to R134 will net you a car that gets cool on the highway but doesnt really work worth a damn when the car is not in motion. It never gets cold. The condensor is just too small and no one actually replaces the hoses as they should.
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