[s-cars] Easy DIY A/C leak diagnosis

[Mark Strangways]

Yes, nitrogen is good for that.
I use it often to test hydronic heating systems prior to pouring concrete or 
adding water.
There are a few instances where a VERY small leak is present, and nitrogen 
will not show it fast enough due to it's larger atom size.
In these cases Helium works very well, as the smaller size of the atom 
allows it to escape from smaller leaks fast. There are also a number of 
"sniffers" that will detect it down to very low PPM.

Mark
----- Original Message ----- 
From: "Vincent Fregeac" <vfregeac at sympatico.ca>
To: <s-car-list at audifans.com>
Sent: Monday, June 13, 2005 12:21 PM
Subject: [s-cars] Easy DIY A/C leak diagnosis


Hi all,

I finally found a competent mechanic to diagnose the leak on my A/C. The
same who cost me 3000$ for the head gasket. And it's the first time I've
seen this kind of procedure to find a leak. Fast, easy and cheap: 45$ to
check the entire system. This procedure is only feasible when all the freon
have leaked out, which is usually the case when you realize you have a leak.

Engine off, plug a nitrogen bottle to the high pressure plug on the
condenser. Bring the pressure to the specified max pressure of the A/C.
Spray a "leak detection fluid" (water and soap) on all parts and hoses. Look
for bubbles. A small leak may take 5-10 min. to make a visible bubble so
spray the entire system first, wait a few minutes and inspect. Voilà. Do not
forget to fully release the nitrogen in the air before you start the car
until the low pressure switch turn off the compressor. The A/C system do not
like to run on nitrogen, he said. By the way, the remaining nitrogen will
also avoid internal corrosion until you repair and refill the system. The
guy said he is able to find even the small leaks who only need a yearly
refill.




Vincent


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