2002 gmc yukon

i have to add freon to ac twice a year. dye in the system indicates no leaks. what is the problem

With the proper UV glasses to give you every chance of finding the leak check very carefuly at the case halves of the compressor, it may look like a discoloration and not a dripping leak. Second place is the rear evaporator/expansion valve (if so equipped with rear AC) then check the condensor closely.

If no luck switch to using a electronic detector at all the same places

thanks for the help. i will try it. where do i get the “proper UV glasses”. at a auto parts dealer? what if it is the case halves of the compressor? is that time for a new compressor?

I would not want to bet Harbor Freight does not have these glasses, perhaps your first place to look. If you are the 'go for it" type just walk up to the door of the next Snap-on, Matco, Mac, Matco tool truck you see parked at a shop, Sears may even have these,for that matter even a NAPA store would be good to check.I did not mention that you will also need a UV light source.

If you see the dye residue at the case halves on the compressor it is compressor replacement time (and accumulator and orfice tube). You may keep your eyes open for your next tool (the electronic leak detector) if no leak is indicated with the dye.

Oldschool, do you mean glasses that protect the eyes from UV light? If so, just about any safety glasses will work fine. They are usually polycarbonate, and that is a great UV blocker.

No, he means glasses and a light source so that the yellow dye in the a/c will fluoresce so you can find the leak. I got mine at Autozone.