whistling during acceleration with AC on

[hambone1983]

Folks, I am still new with my 2006 X5 4.4i - and been noticing that while driving on the road, about 40~50 mph and above, there is a whistling noise from the front, this only happens with the ac on. If i turn the ac off, the noise goes away within 10 seconds. If i let off the gas pedal, the noise goes away, so its tied somehow to the acceleration + AC on.

I've cleaned the ducts for any blockage, leaves, etc. The cabin air filter is clean too. All hoses look good and the the serpentine belts have been replaced.

This only happens with the ac on and when off, its a quiet ride. Any ideas? thanks.

[01X5Guy]

Aux fan in front of radiator?

[hambone1983]

my X5 does not have the large aux fan infront of the radiator. I checked some other x5's and they didnt have it either.

[01X5Guy]

Well then - I have no idea. I didn't even realize later models do not have the aux fan.

[hambone1983]

yeah im wondering if its something to do with the ac compressor maybe.

[haigha]

I got a similar noise when the refrigerant (R-134a) was low. Don't know if you have the same problem but you might want to start by having that checked. 2004 4.4i.

[hambone1983]

Did you just refill the refrigerant? or was there more to the low refrigerant fix?

thanks,

Originally Posted by haigha

I got a similar noise when the refrigerant (R-134a) was low. Don't know if you have the same problem but you might want to start by having that checked. 2004 4.4i.

[haigha]

Originally Posted by hambone1983

Did you just refill the refrigerant? or was there more to the low refrigerant fix?

Just refilled it. But, as Weasel recommends, make sure you use a shop with the correct equipment. The system only takes 0.98 lbs which is hard to measure accurately with a simple gauge. My 2004 was down almost a whole can.

[hambone1983]

good point - was there a leak on your x5? to know why it was low?

[haigha]

Originally Posted by hambone1983

good point - was there a leak on your x5? to know why it was low?

It's almost 7 years old. My mechanic said losing some refrigerant is normal over time, especially in a dry climate. He wasn't too concerned but said to keep an eye the AC's effectiveness. This was the first time any was added.