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I noticed yesterday that the vehicle I'm driving (2011 or 2012 Hyundai Accent "Blue"), is slowly leaking a cold, clear, mostly odourless, bad tasting fluid.

Based on the colour and temperature I imagine this can't be A/C fluid, oil, gasoline, coolant, transmission fluid. About the only thing I could think of was that this was either water for the wipers - but the leak is not directly under the engine bay, and why would piping run under the vehicle?

The only other thing I could think of was that this is from condensation - something to do with one of the A/C components. I am using the A/C system heavily as currently where I'm staying is around 20C at night, never mind during the day.

How can I troubleshoot this further? (one idea: check if fluids are leaking with the vehicle off, then on, then on with A/C, and repeat this test after getting home once the car is warm and has been driven for a while). My other idea was to dump food colouring into my water reservoir and see if the leak colour changes.

And - how likely is it that I'm correct in my assumption of what this liquid is? Do I need to be concerned?

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up vote 4 down vote accepted

I think you are correct in diagnosing this as condensation.

Please don't taste anything that comes out of your car!

Here are my suggestions for confirming that hypothesis:

  1. Put down a big sheet of butcher paper (or similar cheap light colored paper that will show leaks) on a dry spot where you will be parking after running the AC for a while.

  2. Pull the car over the paper. Make some reference marks on the paper to note the exact position of the car: e.g., door edge, wheel arch rear & front, license plate edges, etc.

  3. Turn the car off and wait about five minutes.

  4. Pull the car back off the paper and examine.

What I would expect to see is a distinct puddle of (possibly nasty) water underneath the evaporator drain hose. This should be on the passenger side of the firewall and there's an obvious hose that, if you crawled under there, would still be wet.

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Thank you. Why not taste? I of course just tasted a tiny amount, and spat afterwards. – Harv Jan 12 '12 at 22:50
@Harv, because most of what might come out of your car is toxic. Depending on your tongue, taste alone might not distinguish engine coolant from air conditioning condensation. The ethylene glycol in the coolant and the bacteria breeding in and around your condensation hose are both very bad for you. Smell, on the other hand, is an excellent way to distinguish one fluid from another. For example, gear oil and engine oil smell very different (to me). – Bob Cross Jan 13 '12 at 4:27
How old are you? Life Lesson: Don't put anything in your mouth if you're not sure of what it is. What if it was spilled battery acid? – Nick G Mar 2 at 16:09

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