I have searched high and low through this forum for someone with a similar problem, so please don't get upset if I mistakenly duplicated an already posted issue. I hear a weird knocking sound when the air is on. I believe it is coming from the passenger floorboard, but I'm not for certain. I do know it is in the fan because it immediately goes away when I turn the AC/heat off. It doesn't happen all the time, but the odd thing is this. It happens when slowing down and turning left. I know it sounds crazy, but it's true. I have disassembled the right panel down to the cabin air filter thinking that maybe something was loose, but the sound persists. Is the blower fan uneven? Is there a way to disassemble the white box that contains the fan? Is there somewhere else I need to check? I am open to any suggestions.

 

Does it do it when the compressor is disengaged? (Press the AC button until it doesn't light, the compressor will run even with the heat on to dry the air)

 

Does it sound like a rollercoster chain (when climbing) ?

Its the compressor

 

i belive there is a TSB for it. i had a problem like that when i had warranty
its the ac clutch or something like that

 

oh yea? I wonder if the CPO covers this. You have a link to the TSB?

 

The TSB is only for 03.0s

That's why we have a different belt size.
My compressor is noisy, drives me nuts

 

^ lol I can only hear mine if I am idling.

 

Service Bulletin Num : 02056 Date of Bulletin: OCT 01, 2002
Type: Sedan
Component: EQUIPMENT:ELECTRICAL:AIR CONDITIONER
Summary: BUZZ OR GROWL TYPE NOISE FROM ENGINE AREA WITH AIR CONDITIONER ON. *TT
If a 2003 G35 Sedan has: a buzz or growl type noise from the engine area with the Air Conditioner "ON," which goes away when the Air Conditioner is turned "OFF," Refer to the Service Procedure in this bulletin to help identify if the noise is coming from the A/C system. If it is, install the Air Conditioner Kit parts to complete the Service Procedure and reduce the noise, if it should occur.


found here
https://g35driver.com/forums/tsb-tec...list-tsbs.html

 

ah yep 03 only. Mine sounds like a roller coaster lol

 

The sound occurs even when the AC is off which leads me to think it is in the blower. The thing that puzzles me is why is it more prominent when I make a left turn? Is it possible that the blower fan could be out of balance?

 

Mine's bad too. Will a dealer still fix this?

 

^Sure, for about $1500

 

in your original post you said it occurs when the AC is on???
so is it when its on or of?

 

AC/Heating was meant to imply that the sound occurs with both cool air and warm air. To clear up any confusion, yes, it happens when the AC is on AND when the AC is off.

 

yeh i dunno buddy i had a noise like that when i had the ac on, it was like a crackling noise, crackling grinding. good luck man! i hate trying to find a problem life is so much easier when you know what the problem is and you just have to fix it, but diagnosing it sucks