47-55.1 Need help find AC leak?

[PDW HOTRODS]

I am installing a new Vintage Air kit on my 1950 and I have a problem. I have evacuated the system and it will not hold a vacuum. I can put about 28" of vacuum in and close it and it leaks off in less than a minute. I have checked each fitting and O ring. No change. Then I replaced each O ring to be sure and still no change. I can't find the leak using vacuum. I know not to put air in it because of moisture, is there any other way to find the leak? Do I need to charge the system to find it? I thought you need to have vacuum in it to charge it? Thanks.

[Killer Bee]

uv dye injection, our guys have found some odd leaks that way..

one that comes to mind, the seams of a compressor housing leaking, tough one to find otherwise..

evaporator leaks are tough too, but dye will usually work it's way down the condensate drain and let you know..

lots of kits out there, one's I buy for the shops are green plastic folding case from grainger..

sure there's a bunch of youtubes showing how it's done too..

good luck!

[PDW HOTRODS]

Do I need to put a full charge on it with the dye? Or just some charge? When done will the dye be hard to clean up? Will it hurt paint? Thanks.

[MiraclePieCo]

Any automotive repair shop can use an AC "sniffer," an instrument that detects and pinpoints the slightest molecules of airborne refrigerant.

[Wrenchbender Ret]

Make sure its not your gauge connections leaking. Disconnect the high side hose & put the cap on. then try just using the low side. You may have to sacrifice a can of Freon & charge it with one can. Then you can listen for the leak or put some liquid soap around suspected leak spots. Most of the time when I can't contain the vacuum it has been my equipment. Of coarse my equipment is 60 years old.
George

[dsraven]

use nitrogen to pressure up the system, then soapy water to find the bubbles where the leak is. thats what a/c shops do. they can get into a whack of trouble if they use freon to leak test because its not environmentally friendly. check anywhere there is a connection because the O rings in the connection can leak. the seal behind the clutch is another common one. check for any damages on the condensor or other parts that may indicate where a leak may be.

[jbarron]

WrenchBenderRet is on the right track.
Had as bad schrader valve on the high side on the last one I did.
Chased every other connector down first and they where all good.