Having trouble finding AC leak

Joined
Apr 7, 2010
Messages
914
Location
Miami
vehicle: 1991 Toyota Previa.
Problem: filled vehicle with 134a, AC worked fine for 2 days. Refrigerant leaked out by 3rd day.

attempted so far: inserted 134a with dye into system. Leaked out within 3 days. Visually inspected front evaporator, drier, condenser. No trace of dye. Compressor also showed no dye seepage. This vehicle does have a rear evaporator unit. I have not inspected it since it is a pain to access. would renting a sniffer help? I was under the impression they are not reliable.

what am I missing? How can I find this mysterious leak? Thanks for the input.
 
I have not used one, but my understanding is most dyes are designed to only shine when you shine a UV light on them, and usually you do it at night, because It probably will not show up if there is too much light.
 
The two common areas of leaks are the seals on the compressor, and the bottom of the condenser coil on the front of the vehicle, because of salt in the winter. But leaks do also happen in other places sometimes.
 
I used a UV light in the pitch dark garage at night, no trace of UV dye anywhere. I did not see any dye at the drier. Are there any other ways to test for a leak? Using the hissing sound, is that something that maybe I could rent?
 
You will need a quality "sniffer" (not a cheap one) one that can detect even the slightest leak. Go over every joint carefully including the compressor. Make sure to include the rear evaporator too. Go slow, if it's leaking, you will find it. A leak the size that would discharge the system in three days shouldn't be that hard to find.
 
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I had good luck with a sniffer. You have to be patient and take your time going over all the connections, along the hoses, etc. and make sure the system has a slight charge in it so the sniffer has something to actually sniff. If the refigerent leaked out that quickly you have big leak. Also look for oily residue on AC components, sometimes it's coated with dirt.
 
I used a UV light in the pitch dark garage at night, no trace of UV dye anywhere. I did not see any dye at the drier. Are there any other ways to test for a leak? Using the hissing sound, is that something that maybe I could rent?

Exactly which UV light did you use? Those 7 or 9 LED lights are useless. You really need to use a UV light that has like 50 or 100 LED's. Yes, this is based on personal experience.
 
How about going old school and use Dawn and water in a spray bottle. I have found AC leaks that way many years ago.....
 
I will try that cheap leak sniffer. I did not use fancy UV light, just the one that came with the dye. I rather use the spray method if the sniffer fails. There are a few places spraying liquid would require significant tear down.
 
I will try that cheap leak sniffer. I did not use fancy UV light, just the one that came with the dye. I rather use the spray method if the sniffer fails. There are a few places spraying liquid would require significant tear down.
I think you will be impressed by how sensitive the Elitech sniffer works. To be honest, I had modest expectations and was very surprised at the ease of using it and how quickly it pinpointed the tiny leak. I had to add a can of freon to the Accord once a month, so my leak was not as severe as yours. Even if I don't use it again for years, it was money well spent.
 
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