AC Leak Testing - Tips?

[Beachdrifter]

Hi all,


A few years ago I replaced my AC compressor, condensor, accumulator, but left in the lines and evaporator. I might be getting leaks from the lines, or who knows.

I've always had a small leak, but I've decided to figure that one out finally.

I'm using Freeze 12, which works pretty well.

Anyways, what methods do you use to detect a leak? How is a leak detected? I'm trying to do this myself since I've done most of the harder AC stuff lready.

I've heard you need some special dye, and light. Can someone give me more details as to what to use, how to, and where to find it?

Thanks so much,

--Randy

[content22207]

If the leak is small enough, you are probably wasting your time looking for it (or even worse, you risk damaging a thin walled component trying to stop it -- can I hear an "Amen" Farrar?).

People are totally schizophrenic about automotive A/C system leakage. Are you surprised that your 30 PSI tires lose air over time? Why then should your 100 PSI A/C system be any different? (That's just static pressure -- with a refrigeration cycle going, the high side climbs between 200 and 300 PSI).

Household refrigerators don't typically lose freon because their components are soldered together. They also do not have any rubber hoses.

If you still want to try to find a leak, the cheapest and easiest thing to do is pressurize the system with an air compressor, then start swabbing fittings and hoses with soapy water (just like looking for a gas line leak).

Bill Robertson
#5939

[Jacko]

Hi all,


A few years ago I replaced my AC compressor, condensor, accumulator, but left in the lines and evaporator. I might be getting leaks from the lines, or who knows.

I've always had a small leak, but I've decided to figure that one out finally.

I'm using Freeze 12, which works pretty well.

Anyways, what methods do you use to detect a leak? How is a leak detected? I'm trying to do this myself since I've done most of the harder AC stuff lready.

I've heard you need some special dye, and light. Can someone give me more details as to what to use, how to, and where to find it?

Thanks so much,

--RandyHey Randy,

I know where you're coming from. After avoiding ac work for years I bought the gauges and stuff and have started doing my own maintenance. Regarding leak finding one convenient clue is the oil contained in the ac system itself. Generally, where there is a leak will be highlighted by an oily spot ... that's how I found the leak in 4915. I confirmed it with the electronic leak detector I'd just bought but the leak was pretty obvious. Of course if the leak is somewhere you can't see ...

[Chris4099]

Freeze 12 is mostly R-134a plus a few add-ons to make it compatible with mineral oil. Original hoses were not designed for R-134a and will leak faster over time versus R-12. I have the newer type of hoses and my system hasn't leaked any R-134a over the last two years (no recharge required and still cooling just fine). So there probably isn't much you can do after confirming there's no major leak.

Since Freeze 12 is a mixture, you technically can't top it off either (throws the mixture off). So I would consider the newer style hoses and straight R-134a. After that, you should be set!

[Bitsyncmaster]

What I found to be my leak (running R-134a) was the short hose from the condenser to the accumulator. It was a slow leak (about 2 to 3 months) so your not going to find it with any home type detection.

I did replace the long hoses first so maybe those also need replacement when running 134a.

It's been about 8 months since I charged it last and still going strong.

[stevedmc]

Definately check the connections to your accumulator and condensor. I had a mechanic convert my system about 6 months ago when it was in the shop for some insurance work. The AC worked fine for a month or so but eventualyl the r134a leaked out. After inspecting things I found the connections to the accumulator and condensor were loose. Its stuff like this that encourages me to just do my own work.

[David T]

If the leak is small enough I would not waste my time trying to fix it. If you can't make it though a summer it is bad enough to fix. Don't waste time with the hoses, just replace them. An electronic leak detector is difficult to use because of the fans. I also prefer the pressure type test. You can use pressurized air if it is clean and dry but Nitrogen is preferred. Pressurize and test with a leak testing solution which is soapy water with some glycerin. Difficult to properly check the hoses because of the way they are hidden much of their length. Check every connection, the service fittings and the compressor seal. Replace the valve cores. Check and refill the oil if necessary. Do a sweep charge and evacuate the system for at least an hour before charging with refrigerant.
David Teitelbaum

[tiger38117]

The way to do it right...and only way to really be sure in my opinion...is to evacuate the system and them pressurize it with Nitrogen at 200psi. Since this allows you to have the system under high pressure without the engine and fans making noise, substantial leaks can be heard. Smaller leaks can be chased with soapy water.

Once you get to the point that the system will hold the nitrogen at a set pressure for days without a loss, you know you have beat all the leaks. 1905 held 200psi for over a week.

[dhaney]

The way to do it right...and only way to really be sure in my opinion...is to evacuate the system and them pressurize it with Nitrogen at 200psi. Since this allows you to have the system under high pressure without the engine and fans making noise, substantial leaks can be heard. Smaller leaks can be chased with soapy water.

Once you get to the point that the system will hold the nitrogen at a set pressure for days without a loss, you know you have beat all the leaks. 1905 held 200psi for over a week.

I totally agree. I got tired of my car leaking as well and used this method and the car holds fine. I too kept the nitrogen pressurized for at least a week.

Dan

[dmc6960]

Nitrogen is also far better than compressed air for this testing. Compressed air has a lot of moisture mixed in with it - the very thing you fight to remove with vacuum. Nitrogen is a dry gas.

[Bitsyncmaster]

But will Nitrogen pressure checking determine if your hoses will leak with R134a? It took 2-3 months for my leaky hose to loose about 12 oz. of 134a.

[tiger38117]

But will Nitrogen pressure checking determine if your hoses will leak with R134a? It took 2-3 months for my leaky hose to loose about 12 oz. of 134a.

I run R12 so this I cannot answer.

[Beachdrifter]

Wow, great info guys. Very informative.

I am thinking not too mess with it too much for now, based on what was said, and figure the best way is just to eventually replace the hoses.

My leak is very small because it requires me to charge about every 3 months. No oil is visible either.

MAybe start with the small line between the condenser and accumulator and go from there.

Anyone using Hervey's split lines?

--Randy

[Bitsyncmaster]

Wow, great info guys. Very informative.

I am thinking not too mess with it too much for now, based on what was said, and figure the best way is just to eventually replace the hoses.

My leak is very small because it requires me to charge about every 3 months. No oil is visible either.

MAybe start with the small line between the condenser and accumulator and go from there.

Anyone using Hervey's split lines?

--Randy

I have Hervey's split hoses. From what I saw the short hose was the leaker and did not see any change with the long split hoses. So if you want to just try the short hose it would be a good start. My system is the later style AC system so the short hose has the sight glass which is not really useful with an orifice system.

[Chris4099]

I'm using the split lines. The only issue that some have seen with installation is you need to jack the car up by the body, not frame. When you do it by the body, the frame hangs and gives you just enough clearance to get the lines through. If you jack it up by the frame, the cap may not be big enough. There's also the issue that the compressor fittings are a little different then the stock ends. No problem if you replace both high/low sides at the same time, but will be an issue if you just do one side (not really a recommended idea anyway). Otherwise they are great and seem to hold in the R-134a with no issues or require frequent recharging.