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How to detect an AC refrigerant line leak inisde the wall?

0 votes
From Dennis:

Had a brand new Philco ac unit installed 2 years ago in my 13 year old home. The AC tech that I use said it was time after yearly visits to my home for freon charges, coil replacements, and other problems. A year after installation the unit frooze up and flooded a part of the second floor.

Called AC tech and he recharged the system and said there was a freon leak. He also added a expensive liquid that he said may or may not seal the freon leak. This was in the fall and I did not use the system for approximately 4 to 5 months. I called AC tech for yearly check up in April 2011. He said everything looked good and again he added a little freon. Came back from vacation in July and guess what we are freezing up again on the second floor.

AC tech came out, added a little freon and stated that he would have to repipe my home because he detected a leak in the wall where the cooper pipe on the outside unit goes into the wall that then goes to the upstairs unit. My questiions are as follows:

Is there any way to detect a leak in the wall other than the leak detector the AC tech used that makes a noise? I do not trust that device.
What happens if the home is repiped and a freon leak still exist? Who would be liable? I want to be absoluely sure that this leak exist as the Tech states.

I am tired of dealing with AC issues, as you can probably tell, It is like pouring money down the drain. I want my system to work as it should and not have to worry year to year about freeze ups, soaked rugs, and freon charges. Thanking you in advance.

asked in Cooling System by darekrudy (21,730 points)
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1 Answer

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Hi Dennis,

The best way to test concealed sections of the air conditioning system for leaks is to isolate this particular component from the rest of the system and pressurize it with dry nitrogen. This method would also allow pinpointing the component of the AC system which is responsible for your problems (in case this isn’t inside the wall).

You technician would have to remove the gas from the entire system so it can be re-used after the procedure. Next step is to separate copper lines from the condenser and the coil which can be done right at the final connection to those devices or before the wall penetration and after the exit from the wall cavity. One end of the isolated pipe(s) needs to be sealed and after that pipe pressurized with dry nitrogen.

It may take several hours (or even couple of days) for the small leak to be detected / to show pressure change on the gauge but you’ll know for sure that this particular air conditioning pipe is leaking somewhere inside the wall (or not).

Since you have the entire AC system split into 3 pieces, the same procedure can be applied to the condensing unit and the coil to determine their integrity.
I hope this will help, let me know.
answered by darekrudy (21,730 points)