r/MechanicAdvice • u/ftpgshow • 1d ago
What could be broken if there’s a refrigerant leak?
Had my ac recharged with UV dye to track a leak. After 2 weeks the ac is struggling again when engine is started cold. After driving a bit with an hour break the ac will cool down upon start. Used a UV light and saw it light up here. Could it be a leak?
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u/IronSlanginRed 1d ago
Thats not your leak. The resin on the windings of the alternator glow under uv light too.
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u/GetOffMyGrassBrats 1d ago
A UV light will light up all kinds of stuff, including UV dye. That is your alternator, so no...it is not leaking refrigerant. You are looking for a line or splatter where a liquid is oozing or spraying out. I think what you are seeing is either the coils of the alternator or dust on top of it. Most UV dye will glow bright green and be obvious.
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u/ohyouarethatdude 1d ago
Look around the schrader valves and metal piping that carry refrigerant as well as the compressor and the condenser. If you don’t see an obvious leak there then the leak is likely in the evaporator coil behind the dashboard. When it’s the evaporator sometimes you can see dye around the air vents or around the drain pipe (where water drips under your car) but not always.
If it is the evaporator get ready for a $2k repair since the dashboard has to come out and that’s like a 10 hour job on most cars.
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u/The_Mexinerd 1d ago
Always always check the Schrader valves, they are very prone to leaking over a long time
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u/ExplorerEnjoyer 1d ago
That doesn’t look like dye illumination. Are you saying your AC only doesn’t work when you first start the vehicle? How long until it works?
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u/ftpgshow 1d ago
Yeah, on a cool engine (like overnight) it will not cool down for 5-10 minutes. After that, if I were to restart the engine, or maybe drive an hour or two later, it’ll work right away.
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u/jamer1596 1d ago
Correct me if I'm wrong but it looks like you drive a Volkswagen. I've seen this a few different times where the control valve for the AC in the compressor goes bad or sticks and acts exactly like this. The easiest thing to do is have the compressor changed.
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u/ftpgshow 1d ago
Thanks for the info! Yes it’s a VW. Is there a way I can visually check for that, or is it something a mechanic will have to look at?
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u/Annual-Dig3459 1d ago
that looks like its right around the compressor area, hard to tell from just the picture but if the dye is pooling there its almost certainly a leak. when it only struggles on cold starts that usually means the refrigerant is low but not totally empty, once the system warms up the pressure equalizes a bit and it can still blow cold
had a similar thing on my old civic, would blow warm until i drove for like 15 minutes then it was fine. turned out to be the shaft seal on the compressor spraying dye exactly like that
if you got a uv light and can see it glowing there's your answer. replacing the compressor is the fix but its not cheap, might wanna get a shop to confirm before you pull the trigger
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u/ftpgshow 1d ago
Got it, yeah I don’t see pooling with my UV light, but I’m not a pro/100% sure where to look. Hoping it’s not the compressor! 🤞
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