Hissing/scraping noise when AC on...not refrigerant level
Thread Starter
Member
Joined: Mar 2008
Posts: 219
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From: Kansas City, MO
'05 C230K SS
Hissing/scraping noise when AC on...not refrigerant level
I've searched through the stickied HVAC thread, but couldn't find another possible diagnosis in there. 2005 C230 sedan, almost 58,000 miles. For the last couple months, I had been hearing a noise that I would describe more as a very light "scraping" sound (like plastic on plastic, or maybe metal) only when the AC was turned on. I suspected low refrigerant, checked it, and the gauge said it was close to being low, so I filled it up with some 134a. After a week or so, though, the noise is still present. It is intermittent (i.e. not a constant "hiss/scrape"), but pretty consistent. AC blows very cold, but seemed to blow just as cold prior to the refrigerant refill, too.
Is this a leak? Or possibly something worse? Any help is appreciated. I'd like to be armed with some possible causes before I take it in. Thanks.
Is this a leak? Or possibly something worse? Any help is appreciated. I'd like to be armed with some possible causes before I take it in. Thanks.
Member
Joined: Jun 2008
Posts: 89
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From: Houston, TX
2019 E450 Sedan 4Matic
Its like an annoying loud whirling sound right? I have that too, have no idea how to fix it or how much it would cost. I think it is a vacuum leak somewhere. So as of now, I just deal with it 
Thread Starter
Member
Joined: Mar 2008
Posts: 219
Likes: 1
From: Kansas City, MO
'05 C230K SS
So some people hear this, but no one has ever had it diagnosed/repaired? I wouldn't be very concerned about it, but I just hadn't heard it at all until the last few months. Something has changed and/or is not working quite right.
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Joined: Feb 2006
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02' C230k Sport Coupe
Mine was doing that too, I'm not sure what it is but I put some freon and the noise is gone. I bought the two bottle special of R134 in advance autoparts and the included gauge showed that it was low (it came with an UV pen to detect leaks too). Oh well, if its a leak then to the shop, if not then the $29.99 was well worth it.
Thread Starter
Member
Joined: Mar 2008
Posts: 219
Likes: 1
From: Kansas City, MO
'05 C230K SS
Mine was doing that too, I'm not sure what it is but I put some freon and the noise is gone. I bought the two bottle special of R134 in advance autoparts and the included gauge showed that it was low (it came with an UV pen to detect leaks too). Oh well, if its a leak then to the shop, if not then the $29.99 was well worth it.
