My car's AC makes a hissing noise when the AC is.

Tiny
SANDRAPURDEU
  • MEMBER
  • 2006 HYUNDAI SONATA
  • 53,000 MILES
My car's ac makes a hissing noise when the ac is engaged. The defrost and just vents running don't make any abnormal noise. The ac still cools but does not cool as well as it did a few months ago. What can I do to fix it?
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Saturday, February 16th, 2013 AT 6:20 AM

18 Replies

Tiny
KHLOW2008
  • MECHANIC
  • 41,815 POSTS
Check the freon and pressure to confirm if they are within specs. You should get an A/C shop to have a look at it.

Hers some guides on A/C, they will help

https://www.2carpros.com/articles/re-charge-an-air-conditioner-system

https://www.2carpros.com/articles/air-conditioner-how-to-add-freon
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Saturday, February 16th, 2013 AT 1:38 PM
Tiny
TDESMUKE1
  • MEMBER
  • 1 POST
  • 2004 HYUNDAI SONATA
  • 6 CYL
  • FWD
  • AUTOMATIC
  • 10,300 MILES
My air was recently charged and was working fine but I traveled 80 miles today and after 20 the air stop blowing really cold all of a sudden. I check under my hood and saw the line that connects from the compressor to the inward section of the dash was frozen like ice. Is this normal and what could the problem be?
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Friday, March 1st, 2019 AT 6:28 PM (Merged)
Tiny
RASMATAZ
  • MECHANIC
  • 75,992 POSTS
Its freezing up due to air and moisture forming ice and blocking the orifice tube-Get it vacuumed out
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Friday, March 1st, 2019 AT 6:28 PM (Merged)
Tiny
FIREFIGHTERDINK
  • MEMBER
  • 1 POST
  • 2001 HYUNDAI SONATA
  • 99,687 MILES
When temp gauge is selected cold it blows out hot air.
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Friday, March 1st, 2019 AT 6:28 PM (Merged)
Tiny
SATURNTECH9
  • MECHANIC
  • 30,870 POSTS
So is the ac compressor coming on when you turn the ac on?
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Friday, March 1st, 2019 AT 6:28 PM (Merged)
Tiny
ETCH2DAY
  • MEMBER
  • 2 POSTS
Have you done any dash work such as replacing stereo? There is a cable that runs down from behind dash heating console to the passenger floor and attaches to a metal pully type thing. Look under the dash at passenger left foot area. There is a silver metal thing hanging down. It should have a cable attached to it. While the ac is on in cold position. Pull it towards the seat. The ac should go cold. Move it back and see if anything changes. If there is no cable attached. Pop off dash and find the cable to reattach it. Cable my just need adjusted if it is attached. This just happened to me this past weekend. Good Luck.
Tracy
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Friday, March 1st, 2019 AT 6:28 PM (Merged)
Tiny
TDIDI
  • MEMBER
  • 4 POSTS
  • 2005 HYUNDAI SONATA
  • 2.7L
  • V6
  • FWD
  • AUTOMATIC
  • 160,000 MILES
My 2005 Sonata blows warm air when A/C is on. The system is fully charged with Freon and the compressor does kick on when set to A/C but yet still blows warm air. What else can I check? There does not appear to be any leaks as the system is holding pressure.
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Friday, March 1st, 2019 AT 6:28 PM (Merged)
Tiny
JACOBANDNICKOLAS
  • MECHANIC
  • 107,922 POSTS
Have you checked the blend air doors They are responsible for providing either heat or AC inside the vehicle.
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Friday, March 1st, 2019 AT 6:28 PM (Merged)
Tiny
TDIDI
  • MEMBER
  • 4 POSTS
Thanks for the reply I will check the blend doors tomorrow but I do want to add that when the compressor is on the low side tubeing should be cold but it's not. Not sure if that means anything different but thought I should add that info
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Friday, March 1st, 2019 AT 6:28 PM (Merged)
Tiny
JACOBANDNICKOLAS
  • MECHANIC
  • 107,922 POSTS
Yes, that makes a big difference. The vent doors won't cause that. IF YOU ARE CERTAIN it is fully charged, I need to know the low and high side pressure readings. Chances are something is plugged.
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Friday, March 1st, 2019 AT 6:28 PM (Merged)
Tiny
TDIDI
  • MEMBER
  • 4 POSTS
I don't have anything to test the high side, and I used a gauge that came with the cam of freon I used, it just indicated that the system was at the proper pressure
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Friday, March 1st, 2019 AT 6:28 PM (Merged)
Tiny
SREILLY8613
  • MEMBER
  • 2 POSTS
  • 2002 HYUNDAI SONATA
  • 173,600 MILES
My air conditioner will blow warm air while in idle, but when I try to turn it on while im driving, white smoke will come from the hood. (On the top by the winshield) I'm truly hoping this can be an easy fix for me, as I am a single mom with limited funds. Could the AC be clogged? Please help!
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Friday, March 1st, 2019 AT 6:28 PM (Merged)
Tiny
JACOBANDNICKOLAS
  • MECHANIC
  • 107,922 POSTS
White smoke? If you open the hood, can you see where it is coming from? Is there any noise associated with this? I am thinking the compressor is locked up and burning the belt, but that would most likely make a noise.

Let me know.
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Friday, March 1st, 2019 AT 6:28 PM (Merged)
Tiny
JACOBANDNICKOLAS
  • MECHANIC
  • 107,922 POSTS
If the system has low side pressure, then there has to be a blockage. I need high side pressures to help pinpoint issues.
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Friday, March 1st, 2019 AT 6:28 PM (Merged)
Tiny
SREILLY8613
  • MEMBER
  • 2 POSTS
I will have to check in the morning, but it only smokes while driving with the AC on. While in idle it just blows warm air. I haven't heard any noise. I'll double check. I just got the car and that was the only thing wrong. I thought I could deal with it, b having a1 year old in the back sweaty and crying has made me realize I really need it! Lol
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Friday, March 1st, 2019 AT 6:28 PM (Merged)
Tiny
JACOBANDNICKOLAS
  • MECHANIC
  • 107,922 POSTS
By the way, what is the low side pressure?
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Friday, March 1st, 2019 AT 6:28 PM (Merged)
Tiny
JACOBANDNICKOLAS
  • MECHANIC
  • 107,922 POSTS
Let me know what you find.
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Friday, March 1st, 2019 AT 6:28 PM (Merged)
Tiny
TDIDI
  • MEMBER
  • 4 POSTS
I don't know the exact pressure, the gauge I used just used colors to indicate under charged, charged, or over charged. I will see if I can borrow a good gauge from someone to read exact hi and low pressure.

Thank You
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Friday, March 1st, 2019 AT 6:28 PM (Merged)

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