# AC/Defogger Noise & Smoke

**URL:** <https://community.cartalk.com/t/ac-defogger-noise-smoke/4504>\
**Category:** Maintenance/Repairs\
**Tags:** airconditioning\
**Created:** [September 12, 2007, 4:38pm UTC](https://community.cartalk.com/t/ac-defogger-noise-smoke/4504 "2007-09-12T16:38:38Z")\
**Posts on this page:** 3\
**Page:** 1

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**Author:** ![msjaye](https://avatars.discourse-cdn.com/v4/letter/m/ea5d25/32.png) [@msjaye](https://community.cartalk.com/u/msjaye)\
**Post date:** [September 12, 2007, 4:38pm UTC](https://community.cartalk.com/t/ac-defogger-noise-smoke/4504/1 "2007-09-12T16:38:38Z")

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I’ve begun hearing a strange noise when the ac or defogger is in use. It makes a ssshhhhh sound. Then as I was driving white smoke began coming out of the vents. Before I take to mechanic can anyone give me some info on what could be wrong? I drive a 2005 pontiac vibe

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**Author:** ![Joseph\_E\_Meehan](https://sea1.discourse-cdn.com/cartalk/user_avatar/community.cartalk.com/joseph_e_meehan/32/21_2.png) [@Joseph\_E\_Meehan](https://community.cartalk.com/u/Joseph_E_Meehan)\
**Post date:** [September 12, 2007, 5:34pm UTC](https://community.cartalk.com/t/ac-defogger-noise-smoke/4504/2 "2007-09-12T17:34:26Z")

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```
The sound is likely a leak. Three things can leak in there. Coolant (the heater core or hoses) Refrigerant from the A/C or air from the blend doors that are operated on a vacuum.  

The cheapest would likely be the blend door, but it would not make the smoke. Either of the other two could make the smoke. 

Does the smoke smell sweet?
```

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**Author:** ![SteveF](https://sea1.discourse-cdn.com/cartalk/user_avatar/community.cartalk.com/stevef/32/2_2.png) [@SteveF](https://community.cartalk.com/u/SteveF)\
**Post date:** [September 12, 2007, 5:35pm UTC](https://community.cartalk.com/t/ac-defogger-noise-smoke/4504/3 "2007-09-12T17:35:34Z")

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Your description of the hissing sound is too vague to be of any use. I won’t even try to guess.

The “white smoke” that you sometimes see is no doubt just water vapor. It is like seeing your breath on a cold day. It occurs whenever warm, moist air meets cold, dry air. It is harmless and it even provides assurance that your A/C is working strongly.

Since you have no real complaints about your A/C’s operation you might even change your mind about going for service.