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#1
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Hissing sound comming from the A/C
2002 E320. The AC makes a hissing sound once in a while. I took it into the shop and they said it blows cold and everything is fine. I told them it might me freeon. They said there is nothing wrong and it blows cold. I think I might have a leak? Or could it really need freeon?
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2015 ML350 4Matic. Wifes DD 2015 GLK350 4Matic. My winter DD 2012 E350 4Matic. Road Trip car 2009 CLK350 Coupe Designo.Kleemann Tune For nice days/DD 2006 CL600. V12.Eurocharged Tune. Enough said 2005 CLK55 AMG Coupe.Kleemann Tune. For the sound and style 2004 CLK320 Cabriolet. 2005+ Interior swap. For the sunny Florida days & beach days |
#2
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There is only one way to know for sure if you are low on refrigerant (but technically, what you use is called Suva rather than Freon), and that is to reclaim and weigh what is in there now.
Has the system been serviced in the past? It will naturally leak a bit, so if it is the original charge it is likely to be low. Low refrigerant level causes insufficient oil return to the compressor before it causes the system to start to blow warm. Insufficient oil return causes compressor damage. |
#3
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I've seen a lot of AC units hiss from time to time; usually when you kill the engine, but many times when the compressor cycled on/off while modulating the temp in the car. I always assumed it was normal noise from the expansion valve; but come to think of it, I don't think my MB has ever hissed. But, if the shop checked the pressures and they were proper, and it cools well, I guess we could assume the freon is sufficient. Since the acumulator holds the excess freon, and is on the high side, and the compressor gets it's freon/oil supply from the low side, I would again assume that the expansion valve is flowing all the freon/oil the system is requesting, and all should be fine.
Doing a lot of logical "assuming" though, I'm certainly not an AC guru. DG |
#4
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The problem is that while the refrigerant does return, the oil doesn't do so well in an undercharged system.
http://www.airsept.com/Articles/RecycleGuard/Motor0403.pdf Quote:
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