Last December I bought a new 2005 Nissan Altima 3.5 SE. I love the car, except for one thing. When the weather is cold, the blower fan on the automatic ventilation system makes a very high pitched whistle when the fan is blowing fairly hard.
The sound drives me crazy - fingernails-on-the-chalkboard crazy. It is so high that you can even hear it over a loud radio. It's too high for me to hear in my left ear. I only hear it in my right, no matter where I sit in the car. My wife has better ears than me, and she can hear it in both ears. Of course, the guys at the dealership can't hear it at all, probably because of too many years of loud rock music.
Right after I bought the car, I complained to the dealership. They replaced the blower, but it made no difference. They then put yet another blower in and also replaced the blower housing, but it still didn't fix it. Then the weather warmed up and the sound went away. Well, it's winter again, and the sound is back as annoying as ever.
The sound isn't steady. It is constantly varying in intensity. It's very high pitched; if it were any higher no one but the dogs would be able to hear it. I'd describe it as a whistle or a whine or a squeak, or as air leaking out of something, or like the whistling sound you make by blowing on a blade of grass or a piece of paper. It sounds like the whistle of air more than a mechanical sound like a squeaky bearing. It only happens at medium-high fan speeds on cold days, below freezing. I think it's loudest on the coldest days. Engine temperature doesn't seem to affect it. It doesn't occur at low fan speeds or when the fan is blowing full blast. I never heard it during the summer, even when the AC was on. I can't localize which direction it is coming from, probably because I can only hear it in one ear. Since the ventilation system is automatic, I can't ever predict when the fan speed will change just enough to make the horrible noise and shock me back from my crusin-in-my-Altima bliss.
Thanks for any suggestions you can give me,
Larry