Universe93

I've been noticing an almost constant hissing sound coming when the A/C is on during the afternoon drive home from work, on my 2013 ES350 with 75k miles. Now, the temperature in central NC is above 90 degrees and extremely high humidity, the dew point is consistently over 70 so I'm sure the A/C system has to work hard. Father's day and Monday has the temps at 97.

Is this a common sound or constant hissing is not good? I know the expansion valve opens up and there is hissing from A/C units for several seconds but this is constant. But the air is very cold and no issues at all. Recent trip to the private Japanese mechanic showed no problems or leaks.

More important though, hope the house A/C units and system are up to the upcoming 97 degree test!

bc6152

I have a 2013 350 and also hear a slight hissing sound. Air is cold and works perfectly. Believe that you have no issue...

Poppa

Just wanted to say I live in Louisiana.. hot as hell and really humid. I can not say that I have heard any hissing sounds at all with my a/c. Mine is a 2013 and so far a/c has run flawlessly..

Roland

newyerker

well i know CO has different climate with almost no humidity, but it has been scorching here but the only hissing i hear is only when the vent seats are on.

pab12

>also hear a slight hissing sound.
Do you have the cooled seats? I do and also have heard a hissing sound.
I think (...) it has to do with the seat cooling. My hunch is that the car periodically releases a blast of cold air to the seat rather than a steady flow.
But if someone knows otherwise, I'd be happy to learn about it.

Mike728

The seats are not cooled. There's just a fan under each seat.

LexBob2

This is a always a good reminder. It keeps expectations realistic knowing the seats are ventilated vs. cooled.

BradTank

Are you possibly talking about the fans on the seats? They make a lot of noise if you move position, took me a while to figure out. One minute dead silent, but if you say move your shoulders, it can be loud. Thought something like a wheel bearing was going out in my car at first.


But if ice cold air is coming out the AC, it's probably working properly. Lexus AC is just about the best of any other car brand, I live in AZ and it gets the car cold. The European car companies though do a terrible job in my experience.
Maybe try experimenting and open up the back vents, close the back vents, etc and see if the hiss changes.

I have though noticed "loud" blend door motors when I sometimes adjust the temperature, but it's not a hissing noise. Sounds like an electric motor.

zes

Better be careful using the ES A/C in humid weather. I made the mistake of leaving mine in "Auto" when I lived in Columbus, Ohio. In "Auto" it defaults to recirc mode. The result was that in a couple of years I had a major mold problem in the evaporator. It stank real bad and took two doses of anti mold treatment by the dealer (I paid for only one treatment and they gave the second treatment free) to get rid of the smell.
After that I always make sure to switch it to "Fresh" as soon as I turn on the A/C and turn off the A/C about 5 mins before I get to the destination and crank up the fan to full to dry out the evaporator. Have moved to Colorado so hopefully this will be less of a problem.

yardie876

I live in S Fla where we're basically living underwater and I've never had a problem with mold building up in the evaporator. Of course different car, but I've seen a few talk about mold buildup in the IS, ES, and GS. It seems to be an anomaly and happens randomly to a small handful of cars.

jollick

Same experience here in GA, no ES mold issues. Always in Auto on both ES we own. I wonder if the drain tube may get clogged with a spider or other insect. I had that issue on my 2006 GS300 AWD. A simple thin rod up the drain tube and water came running out, problem solved.

newyerker

welcome to CO!
as a 20 yr coloradan, humidity isnt something we have to worry about but the ES mold def is. keep practicing what you are doing or it will start to smell real soon.
i noticed it on brand new loaners too. i fortunately just never like the idea of recirculating and always leave them open.

Poppa

Thanks for the heads up.. but I have to say I live in Louisiana...has to be one of the most humid places I have ever lived. So far no issues with mold or anything like that.. But I'll keep watch.. thank you again.

Mike728

I'm stating to wonder if the issue is only present in areas that are not the "most" humid. I had the issue when I first picked up my ES. I think I noticed it in like May of 2013, when it's not super humid in Chicago yet. Since switching to outside air on each startup, the issue hasn't reappeared.

lesz

+1
I don't think that I've ever had a mold issue with either the 2013 or 2017 ES, but what was noticeable was that, when I used the recirculate mode, which the system defaults to whenever the outside temperatures are above the low to mid 70s, the cabin air quickly seemed to be somewhat stale, but when I use the fresh air mode, that is not the case. I've gotten into the habit, therefore, of switching to the fresh air mode immediately after each start of the car.