Air Conditioning leak checking / finding information sharing thread

[SirRobyn0]

With summer coming I thought this might be a topic of interest.

So the mission of this thread is for folks talk about the methods they like to use for finding refrigerant leaks in A/C systems. Since 90% are running R134A, I'd like us to mainly focus on that, but most leak checking procedures I know about will work for R134A or R12. I'm hoping that folks will share their methods and also learn from this thread.

So personally I find that finding refrigerant leaks is a pain in the butt. I generally enjoy doing A/C work as most repairs are generally not that hard, but leak checking sucks IMO. The three methods I've uses are the "sniffer" style leak detectors and die. They both suck. The third method being soap and water method.

Lets talk about the sniffers first. All the ones I have used all seem to be prone to giving false positive leak results. Suppose you get a vehicle in your shop, or a personal vehicle and the A/C is flat. So you recharge the system, turn the sniffer on and run it along lines, by the compressor seals, next to the condenser, down the lines and finally in the vents in the car in effort to get it to go off indicating a leak. I use to always have trouble with it going off for no reason, giving false positive results. So much so that I don't use a snuff anymore. Pretty much ever. My newest one is probably 20 years old, perhaps there are better units out there today.

Die. So the principle of the die is that you inject it into the system. The die does not mix with the refrigerant, but it mixes with the oil in the A/C system. Some time later after some of the refrigerant has leaked out you'd shine a black light over the A/C components preferably in a darkened shop hoping to see the UV light die glow at the leak source. The problem is most of the A/C oil is in the compressor, with smaller amounts hanging around in the condenser, evaporator and accumulator. The refrigerant because it is in the system and under pressure does tend to pick up some of the oil, and thereby some the die and carries it around the system. So there is some hope that oil will seep at the leak point and you'd be able to see it that way. I've been able to diagnose a few evaporator leaks by shinning a black light on the condensation water or the housing drain. Sometimes die is really great at finding a leak other times it really sucks, it just depends on whether or not a little bit of oil is getting out with the refrigerant. I really do find that looking for the leak with die and a black light is best done in a shop with most of the lights turned off so it's a big dark or outside after dark.

Soap and water. Just like you'd expect this method involves a spray bottle with a soapy water mixture in it. Spray the soapy water on all the connections and components you can see and look for bubbles, much the same way you might do looking for a leak in a tire. The big downfall to the soapy water method is that it will only work on components you can access, so no way to check the evaporator with soap and water.

What do you guys think? Got questions, ask then. Got tips or another method to share, please do so.

 

[Catbox]

Good idea'r.
I will be battling this on our 1995 Sub this season.
We can pump it up with new juice and it will cool great.
But it only lasts for a few days, that gets expensive.

I have all new stuff sitting in the garage for it, but I would like to find the actual leak too.
Before we change out all the parts and pieces.

In a different lifetime I was a HVAC Service type guy.
I have used the dye many times to find leaks, but auto AC is a bit different.

But of course we are having an wicked early heat wave right now...

 

[Finkaire]

Oil is what circulates the refrigerant through the system. A leak will show up as an oily spot. Dye is used to distinguish one oil leak from another. Look on the underside of your hood for an oily streak indicating a compressor seal. Look closely at both sides of the condenser, again looking for oil. Look closely at all of the lines on the engine side of the firewall. If a leak is not discovered you may have a leak at the evaporator, seepage leaks typically won’t be discovered by a leak detector. A seepage leak must be found visually, you may be able to see a part of the evaporator through removing the resister, also refrigerant is heavier than air so when checking with a detector always go to the underside. Lastly if you have access to the drain tube, that would be a good place to check with a detector. If you have a charge in the system you can also block the radiator with cardboard to build up pressure, making the detector more efficient.

 

[Ricko1966]

I have a sniffer I don't like it. I have a dye kit I like it. I also have an ac fitting with a milton fitting on it so if I got something that's discharged I can blow 100lbs of shop air in and listen, and then get a spray bottle of soapy water. It's a big help.And a Robinaire Vacuum pump.

 

[fast 99]

In the R 12 days no one cared if there was a small leak. Large leaks the sniffers worked. As long as it lasted a season or even a couple months people were happy. On hot days I stood in basically one area and jammed R12 in systems all day 14.95 + $4 a can. With costs today that isn't the case.

Today we use dye and have been very successful finding small leaks. If a dead system holds vacuum, we will add dye. If no leak was located, we recommend they return in a day or so. We can almost always find the problem. Some leaks are very difficult to locate, such as lines under the body on dual systems.

Any vehicle in for major AC repairs such as a compressor we will automatically add dye. If leaks occur later we are able to find it. Several manufacturers put dye in at the factory, they must know something.

Actually, this reminds me need to repair a leaking hard line on my SB. Found with dye.

 

[SirRobyn0]

@Catbox Sounds like my 1996 GC. Last year it would hold a charge for a few weeks at most, so just charged it when it was REALLY hot out. This year it wouldn't hold a charge overnight. It's the evaporator and it's a dash tear off job. I've got the parts. Evaporator, compressor, accumulator, and the main line set. Oh also a heater core. I figure if I'm doing the evaporator may as well. I just need the time to do the work. Looking like probably the weekend after this one coming up.

The guys talking about looking for oil streaks that is very true and can be the key to finding a leak, but for some reason not all leaks show oil. In my experience anyway. Perhaps because the system is low on oil. Or also I think sometimes low side leaks, because the pressure if higher with the system off, can in some cases leak with little to no oil to show.

@fast 99 I just bought R134A for the shop. $289 for a 30lb can was the best I could find. A couple years ago it was $99 for 30 LBS.

 

[fast 99]

I just bought R134A for the shop. $289 for a 30lb can was the best I could find. A couple years ago it was $99 for 30 LBS.

Didn't Ensle put a stop to small 134a cans over the counter?

I bought a couple cases of 134A for myself last year. Only have one vehicle that uses it.

Have around 60lbs of R12 for the other vehicles that use it like the SB. Should last me rest of my life.

This leak chasing will likely get harder with the 1234yf. And of course, every shop needs new equipment. Might be a government conspiracy. lol

 

[SirRobyn0]

Didn't Ensle put a stop to small 134a cans over the counter?

I bought a couple cases of 134A for myself last year. Only have one vehicle that uses it.

Have around 60lbs of R12 for the other vehicles that use it like the SB. Should last me rest of my life.

This leak chasing will likely get harder with the 1234yf. And of course, every shop needs new equipment. Might be a government conspiracy. lol

Yes, Washington state banned over the counter sales of 134a, who the instigator is IDK. I can kind of see both sides of the ban. Making it so Joe blow can't fill top off his car once a week is probably a good thing, but it's inconvenient for those of us that know what they are doing. However I learned just recently talking to the wholesale guy at my local O'rielly's that the wholesale department keeps some of the small cans behind the counter and they will sell to anyone with a section 608 or 609. That's good info for me, I travel around the state a fair bit for the farm, so now I carry a copy of my 609 in my wallet so I can potentially buy a small can if needed on the road.

We have a 1234yf machine at the shop. The machine itself is overly aanal in itself leak checking and processes. Like so many newer systems rolled out on automobiles I have zero desire to work on 1234yf cars, it's just another brick in the wall of me exiting the profession. Also a 10lb container of 1234yf is currently $495.

My square was retrofitted before I bought it so I've left it as 134A. It's good enough. At the shop we have an R-12 machine still but we are now out of R12 and I have no idea where to buy it and know it is good pure R-12, so that might be the end of us filling old rigs with R-12.

Remember when some shops were "retrofitting" R-12 cars to R-22?

 

[fast 99]

134A seems to work decently if converted properly. But we both know 134A isn't as good as R12. I have R12 so no need to change.

Yes I remember R22 and other refrigerants were tried. I know a car dealer in Phoenix bought what he thought was R12, 30lb cans. I saw the cans, they appeared sealed and boxed like new. He used it for about a month before anything showed up, corroded inside. He had to completely replace entire AC systems on around 20 cars.

When Washington enacted the 134A law neither myself or the other tech could find our MACS card, NAPA wouldn't sell to us and wouldn't accept ASE. It was a problem for a while.

The fun is gone. Much of the public thinks we can hook up a scanner and it will tell us what is wrong. When I signed up, what we see daily wasn't explained in the brochure.

I am about to hang it up. Have no idea who is going to fix these mobile computers. None of the new hires we tried could pour water out of a boot.

 

[Hunter79764]

Timely post, I've got a leak I need to find on my motorhome (05 Kodiak chassis). Last summer I had a compressor failure following a leak, replaced the compressor, condenser, 2 of the 3 lines, evaporator, drier, and orifice tube so I'd never have to worry about it again. Drove it this spring, guess what, no AC... Initial dye test didn't show anything, I'm going to put in a can and try the sniffer.

Couple of notes: ALWAYS replace the drier if air gets in a system. Moisture in the air traps in the drier, when it saturates, the moisture can combine with the oil and form acids that eat the system alive. It's great $20 insurance if you care about the vehicle.
Another option that's not as common is to charge the system with dry compressed nitrogen. You can get a modern system to 500 psi for your soap test. Converted R12, you might stop at 400 or less. If you have a shop, then an ultrasonic leak detector unit might be a good addition as well, pressure it up with nitrogen and "hear" the leak, then vacuum it down and the drier stays dry vs using shop air.

And last, one of the better mobile HVAC refrigerants is actually butane (but don't try "converting" your own, there's a lot more to it), it's cheap and efficient and works well with the right system design, but can't be used because the government doesn't want people driving around with compressed flammable liquid in their car. Which is exactly why gasoline in a passenger vehicle is not flammable, and the oil mixed in with the 134a that lets loose under pressure won't create a nice fireball when you give it an ignition source. Oh wait, that might not be true...

 

[fast 99]

Ammonia is also a good refrigerant but has some nasty side effects.

 

[Finkaire]

NOS of R-12 available on Craigslist, price starting to come down as well. Still running R-12 in mine

 

[Hunter79764]

Ammonia is also a good refrigerant but has some nasty side effects.

It's great for low temp stuff. They still use it for supermarket coolers, but usually in a cascade system where the ammonia cools a different fluid outside, then the cool fluid is pumped through so that an ammonia leak doesn't go inside where customers are... Also used in RV fridges in a pretty cool system too. One day I want to build a large scale ammonia chiller, but it's way down on the list.
I used to work as an engineer for Lennox, but I've forgotten more than I remember at this point.

 

[squaredeal91]

2 years ago I bought a kit from a company called red tek and they claim to have a compatible to R12. I ordered one and had success with it on an 89 F250 diesel. Still was mostly full on the 12 but lacked a bit. I put in a can to top off and Worked good enough to blow chrystals out the vents lol.

 

[SirRobyn0]

The fun is gone. Much of the public thinks we can hook up a scanner and it will tell us what is wrong. When I signed up, what we see daily wasn't explained in the brochure.

I am about to hang it up. Have no idea who is going to fix these mobile computers. None of the new hires we tried could pour water out of a boot.

I'm glad I'm not the only guy who feels that way!