13 Jun 2014

How to find small freon leaks

Freon leak repair stories No Comments

How to find small freon leaks


In this post I am going to share with you how to find small refrigerant or freon leaks in a split system air conditioning system.

Many times split system air conditioners will have small leaks where it’s not really a problem if you have the system serviced each year and maybe once every 3-5 years the tech may need to add a little refrigerant. This is not something we worry over. After all someone usually gets to it prior to it being a problem for you. And trying to find a leak this small is difficult.

Then there’s that small leak that is a problem. It looses just enough refrigerant every year so that the coil freezes, it drips water on the floor and there’s no A/C on hot days. The first thing we can do with this type of leak is look in the obvious spots. Exposed solder joints are the first place to look. I usually start out with soap on exposed joints on the condensing unit. I find electronic leak detectors have a hard time finding small leaks outside and the halogen units which are my favorite are hard to see in the sun.

I rarely purchase the bottles of soap leak detector solution from the supply house any more. I use Dawn in one of those water bottles with the little flip cap. But you can use anything you like. I worked with a guy at the Carvel corporation who was from India who said in his country they would shave regular bars of soap and mix it with water. next we can go inside the house and inspect everything visual, then open the coil access and check with your leak detector at this time.

The next step in order not to waste a lot of time is to pump down the condensing unit. There is a trick to this! Your going to run the unit for a few minutes until it is condensing liquid. Then close the high side service valve and let the system pull down. If you don’t let the system run for a while it will never pull down all the way.

Once it has pulled down shut everything off, close the low side valve. using your manifold gauge set add exactly 100psi of nitrogen and let that sit for a few days. When you return if the pressure is still at 100 psi then you can be sure the leak is in the condensing unit. If the pressure has dropped then the leak is in the line set or coil.

if the leak is in the line set or coil you must separate them which will not take much time if your good at working with copper. Of course release the nitrogen first. Now you can charge the high side, the low side line and the coil separately with 100 psi of nitrogen.

which ever one looses pressure must be fixed or replaced.

What if it’s the condensing unit? First thing i do is carefully check all the joints. I remove the screws from the fan motor assembly and lift it out of my way. you can rest it against the house or remove it completely. with power cut to the system of course. next check the compressor terminals. There is not a lot of exposed tubing in a modern split system condensing unit. you should be able to inspect all the tubing and the compressor using soap and a leak detector. If you can’t find anything then it is most likely the coil.

It is very hard to find a leak in the coil.

You can mix up a quart of dawn in a bucket of water and pour it into the coil starting at the top.

Then look very carefully for a long time panning around for the leak. Good luck!

I have taken the coils out and just to satisfy my curiosity sealed the end and filled them with nitrogen and put them in a kiddy pool and sure enough there was the leak or leaks. Sometimes coils become porous from acid rain or maybe they were made poorly. But there won’t be one big leak instead there will be hundreds or even thousands of small leaks.

Many techs will disagree but they are the same people who slap dye in your system. never look for the leak, top it off. Act all arrogant, charge you a lot of money but never actually solve the problem. I have been in this business since 1975. I can find leaks.

If you have a small leak on a new system document everything so your covered. And please dont forget to go online and register your system with in 90 days.

Thanks for reading my post.

Greg Murphy



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