duckJAI

Hey guys, I've had this air conditioning hissing sound from the driver side vent for quite a while. The AC didn't work for a few months as it seems the Freon was empty but anytime the "AC" button was on there would be this hissing sound from the driver side vent and only that side. It is intermittent as well.

I've got my mechanic to fill up the freon, he found a leak from the valve in the engine bay and fixed it. Runs awesome and cold but the hissing sound is still there and evident. It's the same as before intermittent and the sound only comes when the AC button is on.

Any idea what it is? Thanks!

duckJAI

anyone know whats happening?

sakataj

iTrader: (182)

record a video of the "hissing" for me please

StlLexusTe

Might be hearing the freon entering the evaporator. Have had this complaint from customers before. "I cant re-design the car" is the explanation they get from me. LOL

duckJAI

I will look into the engine bay tomorrow to hear if the sound is audiable.

Now I'm also hearing another sound, it sounds like "whooooop" when the A/C is on. This sound is new and only started to hear it after my mechanic recharged the system with Freon. It's like air is in the system and escaping it and making this "whoooop" sound. It's very random and no idea where it's coming from.

sakataj

iTrader: (182)

i have NEVER heard the freon entering the evaporator on my car or any other car i have owned. i am a HVAC guy by trade also.....it shouldn't just ENTER it, as its supposed to be always constantly circulating not some on this side and then whoosh it enters the evaporator...even when the car is off and the froen is just "sitting" there its still in the WHOLE system and not just one side so to say

not to be rude but on your explanation to them


make me a video....and what is your mechanic saying it is? have the pressure readings?

StlLexusTe

Not to be rude, but have you been working on these things for 15 yrs? I know what noise he's talking about, Ive heard it on many cars. When the freon enters the evaporator after going through the expansion valve, it makes a hissing noise. Some of the older RX's were really bad. Its the freon going through the expansion valve that causes it. I know the whole system has freon in it at all times... otherwise it wouldnt cool at all...........

sakataj

iTrader: (182)

no, i havent but i will tell you what i have been doing for the last 10 years... i manage a HVAC SUPPLY HOUSE so i know a thing or two about freon and closed cooling systems. the expansion valve shouldn't make ANY hissing, period! yes i have owned a car where from time to time you could hear the freon passing through the expansion valve but i only heard it as i was listening and i knew what it sounded like. my gf never noticed it and thought i was nuts when i mentioned it as it was REALLY faint and it was also UNDER charged. im not gonna debate this with you as im busy...its peak season at work, so no time for internet fighting.

StlLexusTe

Yes sir. I understand...