# Humming noise when I start the car & AC... :/



## MD-Dubster (Jul 7, 2010)

It started 2 months ago, when I first start my car, there is a humming noise coming from behind the glove compartment area, and the noise goes away after 10-15 seconds and never comes back while driving.

It also makes noise when I first start the A/C... I think the noise is related to that... but I have no clue.

I don't want to scare people when they get in my car... I just want the noise to go away 


Thank you in advance for the help guys... I do appreciate it.


----------



## meshgiath (Jun 4, 2009)

The only noise I got at those times from that area was remedied by this: http://oooo-a3.blogspot.com/2006/01/fuel-line-rattle-fix.html

...but it was a knock/clank/tap noise, not a hum. Worth a shot though - this is a $5 fix. Preventative maintenance if nothing else :thumbup:


----------



## VDubGTi08 (Jan 31, 2008)

Can you remove your glove box and see if you can track the noise down? Can you duplicate the noise when using your recirc. button on your climate control head? Could be some kind of blend door/flap positioning motor on its way out.

Year,Make,Model and what type of climate control do you have? Climatic,Climatronic?


----------



## vliou (Nov 22, 2009)

it's the auxiliary electric fan that comes on when the compressor is engaged


----------



## MD-Dubster (Jul 7, 2010)

Thank YOU for all the replies 






vliou said:


> it's the auxiliary electric fan that comes on when the compressor is engaged


I had few people tell me this... but they weren't sure. 

It is a 2007 GTI, and AC is not Climatronic (no dual temperatures)


Is this a big deal? If I don't fix it, a bigger problem later on? 

Or...

Just deal with annoying noise, replace it if it fully breaks down?



What does the auxiliary electric fan do?


----------



## VDubGTi08 (Jan 31, 2008)

Auxillary electric fan is in the engine bay behind the radiator. I dont know why the noise only lasts for 15 seconds if its the slave fan. That fan should be running all the time when the A/C is on. If it were the fan I would think the noise would be present all the time its running. You also said it happens on start up even if the A/C is off? Does the recirc button make any difference?


----------



## vliou (Nov 22, 2009)

No, recirc does nothing

The auxiliary electric fan may come on or may not come on with the compressor - that is right from your manual. I've noticed that 99% of the time, if the compressor is on, the fan runs.

The fan exists to help cool down the compressor and make it more efficient. Also - it tries to help keep your engine bay cooler to prevent overheating. Imagine a hot summer day, you're idling and your AC is running - this is why american cars overheat and the Germans don't..

Auxiliary electric fans that are not belt driven like the main fan is - you'll notice some american car drivers will purposely idle higher when their sitting around on a hot day - to keep their cars from overheating - while I smile and laugh at them.

A good way to test - open the hood, keep AC off. Note secondary fan not running. Turn AC on, note secondary fan running


----------



## MD-Dubster (Jul 7, 2010)

Yes, the noise always comes on when I start the car.

AC turned ON or OFF.


It lasts around 10 seconds and turns off forever.


----------



## vliou (Nov 22, 2009)

So if you start the car with the AC on and stays on, the secondary fan turns OFF anyways after 10 seconds?? :what:


----------



## VDubGTi08 (Jan 31, 2008)

> No, recirc does nothing


I was asking the OP if the recirc button made a difference, not you. Unless of course you have tried this already on the OP's car.



> The fan exists to help cool down the compressor and make it more efficient. Also - it tries to help keep your engine bay cooler to prevent overheating.


The first part I dont necessarily agree with. The second fan comes on to pull more air across the condensor making the A/C system more efficient, not to blow air onto the compressor itself. The second part of that statement I do agree with. With the A/C on there is more of a load on the engine so it does require more cooling.



> Auxiliary electric fans that are not belt driven like the main fan is -


Not sure if you're stating that the main fan is belt driven on a 2.0T FSI motor or not. FYI the main fan V7 and the Auxillary Fan V177 are both pulse-width modulated fans controlled by the ECM.



> A good way to test - open the hood, keep AC off. Note secondary fan not running. Turn AC on, note secondary fan running


This isn't really the best way to test the fans. On a cold start your fans won't come on until coolant temp has reached a certain level. Then the ECM will command BOTH fans V7 and V177. If one of those fans fails to operate, it will set a DTC in the Address 01 Engine Electronics and eventually turn the MIL on.

When A/C is requested, the ECM will again command both fans on using a PWM signal. If a fan fails to run a DTC is logged and MIL illuminated after a certain number of failures.

If the OP can do some more diagnosing of his vehicle and answer some questions since I cant physically see what is happening than maybe we can get somewhere with this.


----------



## VDubGTi08 (Jan 31, 2008)

To the OP: turn the car on, wait for the noise to happen and finish. Once the noise is no longer present, put the car in reverse with the foot on the brake and wait there. Does the noise come back for a short period of time again?


----------



## MD-Dubster (Jul 7, 2010)

VDubGTi08 said:


> To the OP: turn the car on, wait for the noise to happen and finish. Once the noise is no longer present, put the car in reverse with the foot on the brake and wait there. Does the noise come back for a short period of time again?


Sometimes when I turn the car on, the noise doesn't automatically come on... but it does most of the time.

Other times, the noise comes back after I put the car on reverse, and lasts around 10 seconds again and goes away.

I think we're talking about the samething Mr. VDuB


----------



## VDubGTi08 (Jan 31, 2008)

I would def lead my diagnosis to the Recirc motor. Do you know how to remove the glove box? If not I can take some pics and walk you through it. The recirc function will activate and recirculate cabin air while in reverse to avoid exhaust fumes from entering the cabin.

Ive replaced a few recirc motors because of clicking/stripped gears on 2.5 rabbits. Its a very easy process and shouldnt take more than 30 mins to get the glove box out and recirc motor replaced.

Let me know if you need further help.


----------



## sssupreme (Nov 30, 2008)

I've been having the same problem as you MD-Dubster..It's has happened to me a few times, but not lately, so i haven't really been bothered by it. It's really weird..but this is some great information.


----------



## rippie74 (Sep 26, 2007)

Try turning your a/c on when you have an aftermarket clutch set-up with as single mass flywheel. It sounds like the car is a P.O.S. about to blow up, its funny when people stare @ me like wtf, lol


----------



## jorycurran (Aug 3, 2010)

*humming noise, recirc motor?*

Hi VDub
I know this is Vm forum but I have this exact problem in my 04 Audi A4 Quattro. 
I do not hear the humming at any time, other than when the fan or a/c is on.

I recently had water seeping into my passenger side footwell and my mechanic put the blame on the small a/c drainage tube that runs right behind the radio/temperature controls and to the left of the glove box. He took the glove box out, used compressed air to blow out the connection and the seeping went away. I actually think this was a temporary fix because I have not noticed water leaking out correctly underneath the car since, so I think I have a jam in the drain underneath the battery (which I am still trying to figure out how to remove).

However, just before this issue with the water and since, I have had this humming noise that seems to vibrate the entire dash at times. I also noticed that when I turn the a/c on a higher fan setting - the humming and vibration seems to decrease, as it does when on a setting of 1. But any setting in between very low and high I get this increased humming and vibration. It instantly stops if I turn of the ac/fan or turn off the car. Its nearly consistent to this when using the recirc or econ setting also.

I can feel the piece that is vibrating and humming, its just to the left of the glove box and sticks out just enough that I can see and feel it....and it also seems to get super hot when I have felt it.

I read somewhere that it could be the 'alarm box', i have no clue what this is nor where it is.


Any advice?


----------



## RayGun01 (Feb 15, 2007)

VDubGTi08 said:


> I would def lead my diagnosis to the Recirc motor. Do you know how to remove the glove box? If not I can take some pics and walk you through it. The recirc function will activate and recirculate cabin air while in reverse to avoid exhaust fumes from entering the cabin.
> 
> Ive replaced a few recirc motors because of clicking/stripped gears on 2.5 rabbits. Its a very easy process and shouldnt take more than 30 mins to get the glove box out and recirc motor replaced.
> 
> Let me know if you need further help.


I am having the same problum can you help me? 
It just started today and I want it fixed asap, where can I get the part and how do I put it on 
Thanks for your time


----------



## shamrode (Oct 12, 2010)

*do you hear the noise*

Do you hear the noise when you just turn the key without starting car?


----------



## RayGun01 (Feb 15, 2007)

Yes it dose, it also happens when I push the recycle air button on the AC


----------



## JROBJROB (Jan 13, 2013)

Have you resolved this? I have the same humming noise, starts when i turn the key, lasts for 5 seconds, seems to be around lower glove box area.


----------



## VDubGTi08 (Jan 31, 2008)

Remove glove box, turn key to on position, toggle recirc on and off and listen for noise. Should be coming from recirc motor. Replace motor and reinstall glove box. Should be all set.

Sent from my SGH-T999 using Tapatalk 2


----------



## texanthony17 (Aug 23, 2013)

*It's the expansion valve.*

I recently had my ac serviced because it was blowing cool air instead of cold air in the morning, and warm air when the sun was beating down. One place told me that it was the Compressor, x-valve, and drier than needed to be replaced. I didn't trust them so I got a second opinion and it ended up that on my particular compressor, all you have to do it taking it off and make an internal adjustment to the actual compressor and replace the x-valve as well (mine was clogged anyway). Well, getting back to the humming noise, as soon as they finished, I picked up my car and the humming noise appeared. It turns out the system was not evacuated well when the body shop recharged the system leaving moisture trapped in the system freezing as it exited the expansion valve. You need to evacuate the system, put vacuum on for over 1 hr then recharged.

Good luck.


----------



## MyFastGTI4 (Aug 30, 2016)

*It’s the (TXM) thermal expansion valve and good vacuuming*

So my compressor started knocking so I replaced it with a new one (4 seasons), along with a receiver drier and a thermal expansion valve bought the kit. After the installation I vacuumed the system and charged it with R134A. The next day it started doing the exact same noise as posted in the video above. So I went to the parts store and warranted out the expansion valve. So after I replaced the thermal expansion valve and vacuumed the system for 30 minutes and charged it with the proper amount of refrigerant the problem was fixed no more buzzing. (You’re solution is most likely a new (TXM) thermal expansion valve and a good a/c vacuum and a proper amount of R134a charge and the problem will most likely be fixed. It worked for me.)


----------



## luigi007 (Aug 2, 2013)

Can someone tell me how much it cost to repair this issue?


----------

