Ac Gas noise (Sound like sucking air in)

[AurisA]

Morning/Afternoon/Evening 

i have a concern regarding my AC system. 

When i turn my car on and turn the AC on i hear a strange sound. (Sort of like sucking air into your mouth). It only happens for the first 5 - 10 seconds and goes away. Blows cold air still but i only started hearing this sound during this summer. 

im just curious if this indicates a leak or im running dry on ac gas. i got the AC services a month a go with dealership as it was running low. 

 

Regards

[TonyHSD]

Hi, can you notice when you hear this hissing sound  after you turn ON the  ac will your hvac system goes into recirculating mode ? This is one possible reason. 

[tavy]

  The hissing sound you hear can be due to gas expansion of some AC systems that runs with low pressure freon. To be sure, check with pressure gauge at low pressure port, you should have 2 bars with AC on running at maximum.

  In conclusion, there is not a major problem, the only risk is sometimes evaporator frosts, fills with ice and you can not get cold air enough...

  I have another car that loses freon a little bit, once at two years I have to add 50...60 grams of r134a freon.  The freon I add is r134a that contains compressor oil. I know where it looses freon, at condenser low pressure connector, but I don't change it because it's still OK.

  If AC system looses too much freon, it needs reparation indeed, and complete refilling with vacuuming, adding oil and fill with freon as per car labbel situated under the hood, usually around 500 gr (450...550).

  I hope this helps.

[AisinW]

On 7/13/2023 at 8:00 PM, AurisA said:

Morning/Afternoon/Evening 

i have a concern regarding my AC system. 

When i turn my car on and turn the AC on i hear a strange sound. (Sort of like sucking air into your mouth). It only happens for the first 5 - 10 seconds and goes away. Blows cold air still but i only started hearing this sound during this summer. 

im just curious if this indicates a leak or im running dry on ac gas. i got the AC services a month a go with dealership as it was running low. 

 

Regards

Upload a video so we can help better. From what i understand that is normal sound for the first few minutes and also after the engine is off for the next 15 minutes. Once the compressor is off, the pressure is equilibrating between high and low lines. 

[Cyker]

Is it kindof a wet sucking sloshing sound? That usually indicates insufficient refrigerant, although that would be odd if you only recently had it regassed... I suppose it's possible they put in the wrong amount?

 

[TonyHSD]

Or perhaps there is a leak and the systems is low on gas. 

[Cyker]

The trolley they use to do the regas should pick up leaks and refuse continue, although as I found out they basically don't, so you could be right!

 

[AisinW]

If it is still cold, i won't worry too much. Besides that, they mechanics give us warranty

 

[Saxmaniac]

If you've got a leak big enough to be audible, your system will be completely empty in a very short time. If it appears to work ok, it's probably just the liquid expanding into gas as it's squirted into the evaporator. You'll hear a similar noise jn a domestic fridge or freezer 

[AisinW]

The only time I had leak was evaporator leaks. It was painful expensive.   Suddenly at the end of summer the AC on my Prius 2006 was not cold and I fill it with pure 134A. it works until the rest of winter. In early spring it was not that cold again, so I fill it with another can of 134A. It lasted for about 1 week, and then only 3 days.  Finally, I know something must be leaking somewhere. 

Unfortunately, we cannot use regular Dye for hybrid and my mechanics use electronic detector. The leak was large enough and it was detected from under the dashboard.  

So, if your AC is still cold, do not worry and do not break it.  If we overfill it or adding too much oil/dye/sealer, the performance will be dropped drastically and it is very hard or almost impossible to take overfilled oil/dye/sealer. 

Don't fix if it is not broken.  That's what we deal with almost everything. 

[AurisA]

Hello all 

 

an update. There was a leak somewhere in the system. The culprit was the AC Condenser. It was shattered to bits when he pulled it out. A bit annoyed however because he put a second hand one into my car so it might give me the same problem later down the line. 

 

Also i notice today one of my Coolant line (top one on the resoivoir) is very hot to the touch. Dont know if this is because the mechanic messed with radiator ?