Where's the AC leak?

So is there a common place for AC leaks on a 2005?
I got a recharge with dye but they didn't find any. Worked good for 3 weeks and now is blowing warm again.

 

Did they look at the A/C drain, many times if the evaporator is leaking dye will come out of the drain and also you will get a oil smell when you first turn on the blower.

Sometimes the compressor seal will leak refrigerant and not bring dye with it.

I'd get a UV light and look at every part of the system closely for traces of dye.

 

Is the smell you mention inside the cabin?

 

check the high side hose pipe. Its a rubber to metal part that will eventually get leaks where the rubber and metal meet up. Mine developed a tiny leak and i had to replace it.

if you notice the rubber part coated in grime then its most likely leaking. I cleaned mine off and a week later it was grimey again. A leak test with UV dye confirmed it.

 

Yes, out of the vents.

 

Lot of possibilities on a older vehicle. Check the service valve schraders, check the condenser for rock damage, look at the compressor shaft seal.

You're looking for oily residue, near any connections or fittings.

A 3 week leak is pretty fast, should be leaving some kind of evidence behind for you to find

 

My 06 leak was a gremlin, too. Needed a recharge every summer, but no trace of visible dye. Shop assumed it was behind the dash by/at the coil.

Anyways, replaced my AC clutch a couple weeks ago and found some refrigerant oil slightly oozing out the compressor shaft. There's a felt washer behind the clutch magnet and it had green oil. However, now it seems to be holding coolant, but I think it's hit or miss. My compressor is 17 years old and still going.

 

Sometimes it's easier to find leaks with a sniffer than with a UV light. No direct line of sight required and they are pretty sensitive (controlled with a dial). I find them easier to use than UV lights.

$26 Elitech WJL-6000 Freon Leak Detector Halogen Refrigerant Gas Leak Detector HVAC Tester AC Sniffer R22 R410A R134A 1234YF

https://www.amazon.com/Elitech-WJL-6000-Detector-Refrigerant-Condition/dp/B015FK1EH2

 

A spray bottle with soapy water can be sprayed onto fittings and such, look for bubbles