02 Passat slow leak through evaporator. Dye question

[woodardhsd]

Been dealing with a slow leak in my 02 Passat for the last few years. Usually a decent top-off charge from my can of refrigerant would last all summer. I added some in March, but it was already blowing warmer in June. I finally broke down and took it to a shop for diagnosis. They put dye in the system and figured out that it was leaking from the evaporator because they could see dye coming out of the vents. Price to replace evaporator was around $1100. Not happening on a 15 year old car. I had them fill the system back up and paid the diagnostic fee and left.

I started looking into what it would take to remove the dash and replace the evaporator myself. It looks annoying, but doable. I wanted to see the leaking dye myself before tearing into the car and ordering parts. I bought a UV light kit from Walmart last night to see if I could could confirm the leak location. It's only been a week since I picked up the car from the shop, but I was unable to find any evidence of dye in the vents, or anywhere else.

Is it possible the UV light kit is not working right, is the wrong kind of light for the dye they used? (https://www.walmart.com/ip/UV-Leak-Dete ... t/36156585) Could the dye have dissipated already? I hate to think the shop screwed me. They replaced the compressor on my truck a few years ago and it has worked great since.

[Dougflas]

not all UV lights are the same. Try looking at the condensate drain tube at night. Also, the dye and light you're using may require yellow glasses.

[woodardhsd]

The light came with yellow glasses, I guess I have to use them to see the dye glowing? I figured they were just to protect your eyes from the UV light.

[Cusser]

And got to do this in the dark, or near dark. It sounds though like shop in the past, as well as current shop agree on the leak being evaporator.

I replaced the evaporator in my '88 Mazda truck 15 years ago, is somewhat a pain.

[woodardhsd]

This is actually the first time I've taken it to a shop.

I did attempt to use the light when it was dark outside, but did not use the glasses. If I'm not wearing the glasses will I not be able to see the dye glowing?

[Dougflas]

No you need th4e glasses depending upon the light.