View Full Version : Car vibrates with AC ON

07-22-2010, 09:15 AM

My problem is the following.

On idle, turning AC on makes the car vibrate really hard, i can feel it in the seats, but mostly its shown in the steering wheel, shifter, center armrest.

The problem is for some time, i tried fixing it with the help of Audi forums in Romania, but to no result.

I checked all engine mounts, and mostly anything under the car.
I replaced the following things: front control arms (the whole kit, SWAG), gearbox mounts, rear deck mounts, read wheel bearings.
I checked the car with VAGcom and got no errors, idle is perfect, everything is fine, compressor works perfectly, pressure is ok, engine oil, filters all, replaced in time, new tires, new break disks and pads. The whole car works perfectly except these damn vibrations and the middle exaust has its inside filter or whatever dislocated and vibrates also. But this is recent, the problem with vibrations is 2 months older then this. I cant believe its this.

Also the car performs really poorly when AC is ON, i know its suppose to do like that, but believe me its a little more serious.
The vibrations dissapear 75% mostly if i turn AC off or go ECON.

Car is: Audi A4 B5 Facelift 1999 1.6i gasoline, FWD...

Anyone have any ideea what might cause a problem like this?
All mechanics i went to have no clue, i`m on my own.
Some told me it might be a senzor or something, the car cant tell when AC is ON so the fuel/air mixture remaines the same as when AC is OFF, thuss at idlee it goes under.
Any other details please ask .
Please help if you can....

07-22-2010, 10:04 AM
I would check the blower fan behind the dash, I had a similar problem in my A4, it would virbrate violently when the A/C was on.

07-22-2010, 12:29 PM
My car had a pretty noticeable rumble when the AC was on. The fix ended up being a new AC compressor, even though it worked fine and blew cold air. There is also a belt pulley that is dedicated to the AC belt, and that can sometimes make noise, but that's more of a rattle, where the compressor is more of a rumbling.

07-22-2010, 12:48 PM
i have the same problem i even made a trhead about it 4 days ago but i have stiffer engine mounts +++ my car is the same as urs a4 b5 1.6 1997 the vibration that comes from the ac are effecting only the steering wheel in my case, probably is what one guy told me that i need to adjust my engine mounts, since u changed urs i think is the same problem as mine http://www.audizine.com/forum/showthread.php/376065-Aircodition-and-vibrations

07-22-2010, 01:52 PM
I would check the blower fan behind the dash, I had a similar problem in my A4, it would virbrate violently when the A/C was on.

you know, you might be right. I didnt think a blower could vibrate that hard, but the thing is, ever since i got the car, when i start the car, 2-3 sec later a buzzing sound start behind the dashboard or the stereo; clearly a cooler or something. I might have to check on that. Anyone recomend a tutorial, or is there on the site? I didnt get to check, i`ll look around on the net, maybe i find something.

edit: come to think of it, the same buzzing sound can be heard even with AC turned OFF, and theres no vibrations in the car.

07-22-2010, 04:20 PM
I had the problem with my 1.8t and it turned out to be my MAF. Not so sure if that helps your case though.

07-23-2010, 03:20 AM
i`m sry, what is the MAF and how can i clean it or change it. Where is it?

By this time i`m on to try anything.

07-23-2010, 04:36 AM
i`m sry, what is the MAF and how can i clean it or change it. Where is it?

By this time i`m on to try anything.

it's the air volume meter it's at the right side of ur air box

07-23-2010, 05:54 AM
a, i figured that could be. Is there anything i have to cleen inside, what i mean do i have dismantle to get inside that black tube and clean? I cleaned with cont. spray all contacts i could reach easily 1 month ago thinking it may stop the vibrations. Also cleaned the acceleration thing that lets air inside thingy in winter. Guess i`ll give it a try now anyway

ok, i looked at the MAF thing, its all clean inside, no dust, sparkling. Its clearly not it unless its broken but i dont think so.

07-30-2010, 03:36 AM
bump , help :(

07-31-2010, 02:14 AM
wtf no1? ideeas?

How do i check the accesory belt or bearing etc, i heard that might be responsible. What are the simptoms of a broken one. Any1 have a schematic??

07-31-2010, 05:31 AM
it's a bit difficult since a lot of other markets never got the 1.6 engine.

So the accessory/AC Pulley might be different.

07-31-2010, 07:08 AM
I`ll look around there, maybe i can figure it out.

Also read that my clutch could be tyhe problem, my cluth seems to release very high, not like the first time i got the car. Could it be? Whats the symptom of a worn clutch?

Same read that my injectors could be dirty or some of them could be faulty or spraying bad, having bad presure. What would you recomend? I heard of ultra-sound cleaning.

07-31-2010, 07:21 AM
Disregard the injectors.... where did you get that idea from!!! The car runs fine while without A/C, why would it suddenly vibrate due to factory standard injectors?

Definitely look at the AC system, and isolate every single point of it. Belt, pulleys, compressor (I know you said you checked the compressor but they can cause this issue I believe).
Also the blower.

07-31-2010, 08:22 AM
Does it vibrate at a certain RPM (ac ON or OFF)? Because Idle speed is slightly higher with the AC on. I have stern engine mounts and the vibration is worse with the AC ON vs OFF. (steering wheel also vibrates)

Did you also physically remove the mounts? Or just inspect it from above? My OEM mounts looked perfect, no purple goo, no nothing. But when I removed them, one of them was broken. the bolt on the top was not connected anymore.

07-31-2010, 09:36 AM
ok here it is.

I did a full inspection on all mounts at a service. The engine mounts are all ok (just inspected) they seemed fine, no fluid leak, etc; i replaced the gearbox mounts, they were busted, new spark plugs. Replaced all front arm multi-link set, all rear bushes, front bushes, new oil, new filters, rechecked all electrical connections and cleaned them, new tyres, did a Full Vag: no errors, everything is working perfectly.
The problem appeared suddenly after this winter and it keeps getting worse the more i drive it.
The vibrations arent AC on specific, they are just enhanced by turning AC on. With AC OFF or ECON the vibration goes down somewhat 70% but i bet my pants its not AC related. Its like the idle remains the same as if AC is OFF. If i press the gas pedal just slightly the vibration goes away; 100rpm+ and its gone. Pressing the defrost button also makes the vibration go up by lets say 25%. In the end anything that actually needs power gives vibrations.

Give me a list to go check, what would you do if this happened to you.

-checking the blower is hard? Its somewhere near the battery right?
-would a bad battery be the cause.
-could it be the clutch? I think mine is busted or has 10% life left.
-whats nehind the AC control unit or radio CD unit that spins/moves, a blower or something, something makes weird sound behind it since i got the car, but then it didnt vibrate AT ALL, it was ninja silent.
-one of those metal things that go over the spark plugs had green thing in it, i cleaned it and i think it works now, anyway i can check it, service said its ok.

07-31-2010, 09:48 AM
Best thing to do would be to log the MAF, or swap it with another person to see if that works. I don;t think its half the things you are thinking of.

07-31-2010, 03:18 PM
i think the problen comes only from one of those things. I checked the MAF its squeeky clean, VAGed 1month ago, no errors besides some old ones i fixed and showed good this time.

08-01-2010, 12:18 AM
Check the clutch and pulley on the compressor if you haven't don that already. The a/c sucks quite a bit of power, power that an older 1.6 might not have at idle.

08-01-2010, 07:45 PM
if your saying that the vibration is enhanced by putting the ac on and not created, and you say when you turn on your defroster it goes about 25% louder/more noticeable, im thinking you may have an malfunctioning alternator, primarily the pulley side of it. Your bearings might be shot. As the stator inside the alternator gets loaded by turning electrical components on, it creates more inertia, which you can equate to spinning load. But this must be true as you continue to put loads on the car, you will know your accomplishing this my using a voltmeter on your battery as you continue to put things on, its should be in the range of 12.7-13.8, which is a healthy alternator....just giving another possible prospective.

08-02-2010, 03:35 AM
so i should check how much the alternator puts out witht he car on. If it gives bad numbers its clearly buster, right? I`ll try to look for a voltmeter and check into it.

08-11-2010, 02:48 AM
well i checked, its ALL GOOD. Dunno whatelse to do now, car still shaky inside. I will check my sensors on my climate control unit with the diagnostic codes, maybe detect something but hard to properly understand some of the codes.

10-04-2010, 04:43 PM
hey, bringing this thread back to life.

Vibration comes from somewhere under the AC unit or stick mostly
Will replace spark plug lines soon, and do a ultrasound injector cleaning + test them on the bench, pro thing.

Still looking for someone who replaced the flywheel, could that be it? Also some weird AC problem has recently appeared, check this thread (http://forums.audiworld.com/showthread.php?p=24041840#post24041840)

Maybe its related to the rough idle. Its so rough if i put a key on my armrest, it falls off in 5sec.
Anyone with a similar story?

10-06-2010, 06:10 AM
bought new exhaust bushes for the pipes, will install with the new mid exhaust, maybe one is bad and sends vibrations. As i said the vibrations come from under the middle of the car(transmition) not from the fron of the car, they go less intense as i feel with the hand toward the engine.

btw Anyone have any ideea how to remove the turn signal/hazzard relay from the console of a facelift?

10-19-2010, 05:08 PM
Found this thread LINK (http://www.audizine.com/forum/showthread.php/388815-car-hesitates-when-I-give-it-gas....help) and problem seems the same.
He fixed the rough idle by taking out the throttle body and cleaning it. I can do that but am afraid how to reprogram it or stuff like that, software related.

What should i be prepared to do after cleaning and re-installing ??? Any clues on hot to adapt/re-adapt and/or reprogram the throttle butterfly ??

I bought a VAG-com cable+software, will receive it by the end of the week.
After that i wan`a go for the throttle b removal.

I bet its related to it cause if i do my math it all started just after i cleaned my throttle first time, last winter. I didnt remove it then but cleaned it on position, gently, nothing broken. Bet something is still messed up, and btw i did alot of adaptations from VAG since then, and i got an error last time, cant remember, will post it here if it comes back when i scan .


05-31-2013, 06:59 AM
I have the same problem. http://www.audiforums.com/forum/b6-models-70/audi-a4-1-8t-vibration-143396/page5/ . did you fixed the issue in your car?

05-31-2013, 07:36 AM
I have the same problem. http://www.audiforums.com/forum/b6-models-70/audi-a4-1-8t-vibration-143396/page5/ . did you fixed the issue in your car?

I have the same problem with my 98 A4, it vibrates reasonably when the AC is on.

I haven't found any real solution to this, but at least was able to fix it partially.

How's your car's throttle body looking? I did a throttle body cleaning recently and that reduced the vibration a lot when AC is ON. My car's throttle body looked fine before cleaning except it had some carbon buildup around the edges of the flap and near that little opening where it allows air to be drawn for idling.

So check your throttle body and clean it even if there's only little carbon build up.

05-31-2013, 08:01 AM
I fixed mine by tightening the mounting bolts

05-31-2013, 08:04 AM
Holy gravedig.


05-31-2013, 09:07 AM
We go apeshit when people don't use search, but when they do it's all

"Digging up an old thread, I see..."