I'm chasing down a very small fuel leak in my wing but before I perform any surgery, I would like to vent the fumes in the wing.

The wing has 1/2 gal. unusable fuel and I have left it sit for 2 weeks with all lines, vents, and caps open, with a fan blowing over the fuel filler;  hoping that my 1/2 gallon fuel will evaporate.

Does anyone have any experience using freon to suppress/vent fumes?  I was thinking of introducing a can or two, of R-134 into the fuel return line, with all other openings capped except the wingtip vent line.....or maybe it would be preferable to introduce the freon into the vent line with the main fuel line open??????  The wing is upside down, so I dont think that the slosh door would be a problem.  Any thoughts????? Regards, Bill Hogarty