AC Hissing ??

[okidoki]

Hello friends. My English is not very good. Please excuse me.My car is 2018 Skoda Fabia 1.0 Style. Air conditioner makes a strange sound when it is turned on. Like a buzz. I took the car to the service. They told me this sound came from the compressor. The compressor has been replaced, but it still makes a buzz. I think there's another part that makes this sound. Could this sound be from the expansion valve? Noise before compressor changes https://www.youtube.com/watch?v=HBd7e2OdYwQ Noise after compressorreplacement https://www.youtube.com/watch?v=9dfv3cpnasm The model of the new compressor is 5Q0816803F As you can see, there is no change in sound. The buzz continuesAnyone have experienced this problem? How was it solved? What do you think is the source ofthe buzz? I would be glad if you help me.

[rum4mo]

I might be wrong, but I think that all these small HVAC systems use a fixed orifice and not a thermostatic expansion valve - in the past they did anyway as these compressors have variable displacement so probably no need to have the ability to vary the delivery of pumped fluid/gas AND actively adjust the flow into the evaporator.

 

That probably does not answer your question though, if the compressor is now not causing any noises from itself, then maybe this is as good as it gets, I live in an area of UK that does not "suffer" from much sunlight so don't need to use the AC much!

 

Edit:- hissing noises coming from an operating AC system normally means that the charge level is lower than it should be, these systems get/need to have what is known as a "critical" charge load, which means that they only work well with the correct gas charge or in other words are not tolerant of over charging, slight undercharging can lead to more than normal hissing - and these cars probably don't have much in the way of sound insulation in the area of the orifice and evaporator, maybe something that you need to live with while you own this car.

Edited 27 September, 2019 by rum4mo

[okidoki]

The expansion valve is used to convert high-pressure refrigerant into low-pressure gas. That sound happens because the expansion valve is unable to adjust the pressure. The faulty expansion valve makes this sound continuous. I also often hear the sound of the liquid in the pipes. I was wondering if anyone else has this problem? and what is the solution?

 

 

[rum4mo]

You are correct, VW Group have changed from using a fixed orifice to using a TEV.  As that TEV is mounted at the entry of the evaporator I'd think when your car has very little sound proofing, you will always hear that noise.

[jon15]

Yes, I also hear this sound from my AC sometimes... it's not always present though, so I'm hesitant of taking it in for checkup because I'm sure the mechanics "won't hear anything", or will shrug it off as normal sounds... is it normal, though?

[okidoki]

I don't think that sounds normal. I read in other forums. Sound problem is solved when the expansion valve is replaced. This is a chronic manufacturing error. should not be. Customer service is normal, but there are Fabia cars that don't make that sound. If this sound is normal, why can't it be heard in all Fabia cars? Or why does the sound stop when the expansion valve changes? Skoda service changed my compressor because of this sound. Why did my compressor change if the sound was normal? I think there is no one else in this forum who has this problem or accept it as a problem other than me.