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  #1  
Old 04-17-2008, 12:25 PM
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AC Hissing: Normal?

When AC is on, and especially when accelerator is despressed, there is a hissing sound from behind the dash. Is this normal, or does this indicate I have some sort of leak or low refrigerant?

Seems to cool fine and everything else related to climate control seems fine.

Did some searching, saw a few contradictory opinions on a old post, so I thought I'd see if some others could weigh in.

History, FWIW, is that I had an evaporator leak that I sealed with Cryoseal. That was two years ago....still blowing cold.
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  #2  
Old 04-17-2008, 12:28 PM
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Location: Arlington, Texas
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In our cars it could be a vacum leak or low freon,
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Old 04-17-2008, 12:33 PM
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Quote:
Originally Posted by shertex View Post
When AC is on, and especially when accelerator is despressed, there is a hissing sound from behind the dash. Is this normal, or does this indicate I have some sort of leak or low refrigerant?

Seems to cool fine and everything else related to climate control seems fine.

Did some searching, saw a few contradictory opinions on a old post, so I thought I'd see if some others could weigh in.

History, FWIW, is that I had an evaporator leak that I sealed with Cryoseal. That was two years ago....still blowing cold.
I never heard of Cryoseal, but this hissing matter, well I don't think it is refrigerant because it would be doing this all the time if it was a leak! I would suspect a vacuum leak, but beware of R134A. If this is what your system is recharged with, R134A is deadly and can do serious harm if your breathing it! Fix this right away.

Last edited by Knightrider966; 04-17-2008 at 01:01 PM.
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  #4  
Old 04-17-2008, 12:57 PM
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If it is hissing refrigerant, the hissing isn't refrigerant escaping into the interior, it is refrigerant spraying into the evaporator.
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  #5  
Old 04-17-2008, 01:00 PM
AHH,What's up Doc????
 
Join Date: Jul 2006
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Quote:
Originally Posted by Matt L View Post
If it is hissing refrigerant, the hissing isn't refrigerant escaping into the interior, it is refrigerant spraying into the evaporator.
Yes, it could be refrigerant going through the expansion valve into the evaporator. Sealing up a known leak if your running R134A worries me though. This stuff is known to eat and corrode aluminum!
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