Hissing sound under hood, even hours after car turned off

2015 HYUNDAI ACCENT
37,000 MILES • 1.4L • 4 CYL • 2WD • AUTOMATIC
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2279FD
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Hi, just tonight I noticed a hissing sound coming from somewhere under the hood. the sound is nearer the front lower part (nearer to the ground) somewhere around/behind the radiator area. It is a steady low hiss sound, like the sound of constant air being released from a tire. But it is not coming from the tires. There is no coolant fluid leaking, the fluid's completely full (I had my multi-point inspection last week too).

This hissing sound was still there three hours after I turned the car off and left it parked. And I just checked it again two and a half hours later and it is still hissing a low, steady sound. I sprayed soapy water to the area around the lower radiator that sounds closest to where the sound is coming from, but no air bubbles. If it were radiator pressure it would not be pressurized many hours after the car is off (plus no coolant loss). What in the world can it be?
Oct 29, 2017 at 2:51 AM
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MHPAUTOS
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With the engine off, pump the brakes to evacuate the brake vacuum. just a long shot but see if that stops the noise.
Oct 29, 2017 at 4:53 AM
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PATENTED_REPAIR_PRO
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If this has an air conditioner, perhaps the condenser is leaking. Did the compressor recently stop working? If so, check for a leak around the condenser, it should be just in front of the radiator.
Oct 29, 2017 at 7:20 AM
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2279FD
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Thanks for the suggestions. I absolutely think that it is the condenser that is leaking. See the attached image, that is exactly how the leak looks on my condenser, it sits right in front of the radiator (it looks like a smaller radiator actually, first time I knew that).

Like the picture, most of the face of it is dry but the small lower passenger-side area is wet and there is a slightly moist spot on the plastic car body right under the leaking spot. I went out just now and there was no hissing, I guess it takes it hours for pressure to subside? Then I test drove it around the block (without turning the AC on), came home and heard it slightly hissing again.

I guess it is going keep leaking until it takes all of my AC coolant away. I am guessing either a rock hit it (it is a small,close to the ground car) or the condenser failed due to all of the traffic and hours of driving I had to do on Friday. So, I am going to take it in for the dealer to examine next week, and have it fixed sometime, dealer or otherwise, in November. I do not specifically see the AC covered in my ten year warranty, I have had this almost three years. maybe it is under the five year portion of my warranty? I will find out next week though.

Thanks. If there are any important updates I will write here.
Oct 29, 2017 at 7:47 PM
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STRAILER
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Please let us know what happens so it will help others.

Cheers, Ken
Oct 31, 2017 at 12:08 PM