How to spot a leak

[dorough]

I have another post running in this group - trying to figure out if I have a leak or not. I thought while I'm going at this, that I'd ask everyone.....

What are the various ways to find a leak in the AC system? Is any one method better than the others? What do you look/listen/feel for? Just wonder what all the methods floating around out there may be...

 

[v8318cid]

Look for dark colored grease near any A/C line fittings, takes time to build up usually - indicates leaking o-ring or fitting not properly secured
Check under the belly of the compressor or near the rear for any oily residue - case or o-ring leaks
Use a refrigerant sniffer certified for the type of refrigerant used in the system and examine the system with the sniffer probe - leaks will set off an audible alarm depending on the sniffer.
Install (or check if dealer installed) a UV/florescent(sic?) dye - look for the dye leaking out or use a UV light/glasses to look for leaks.
Mix a solution of water and dish soap (affectionately called bubbly by a few shadetrees I know) and spray on your lines - watch for bubbles forming in the mixture to detect small/pinhole leaks.
For an empty system, use a vacuum pump to draw the system down to as near 30 in/Hg as possible. Turn off the pump and close all open gauge valves. Monitor the vacuum level on the gauges and see if it drops. If the vacuum level drops more than a few points, a leak is possible.
Remove service tap covers and look for dye, oil, or bubbles at the schrader valve. Any of these signs indicate a possible leaky valve.
Certainly not all, but should help.

 

[dorough]

Thank you sir!