Car shakes more when AC is on? - Kia Forte Forum : Sedan / Koup / Forte5 Forums

izzue · 06-21-2011, 09:02 PM

Hi guys i was wondering if its only me but it seems that my SX shakes more under the seat when the AC is on.

wingzero_ · 06-21-2011, 09:15 PM

It is another motor being run by the belt, so it is going to cause some vibrations. You should feel my Mazda with the upgraded rear motor mount on it when I turn on the AC. That would make you complain about vibes.

But I mean if it is just a little different I would chalk it up to normal. But if it is really vibrating abnormally, there may be something wrong like the compressor clutch. When that went on the Eclipse it vibrated a bit more than usual.

xbeastxmode · 06-21-2011, 09:22 PM

When I turn my AC on my rpm goes up like 500, and its a tad louder

trevorusn · 06-21-2011, 09:37 PM

Not much noticeably different, except my gas gets sucked down quicker, but it's all natural. Mine as well may go up 500 rpm, if that, but that's about it.

haydenks · 06-22-2011, 07:15 AM

I have the same condition on my 2010 SX. I've noticed that the a/c doesn't seem to affect either engine responsiveness or gas mileage when it's on.

SimonSayz · 06-22-2011, 10:29 AM

shakes???

mine doesn't, the only difference i see is my gas gets used up much quicker

gtman55 · 06-22-2011, 10:47 AM

Shakes under the seat?

Do you mean it idles a little rougher?

AutoItKing · 06-22-2011, 12:02 PM

Four bangers are notorious for vibrating at idle. Especially with the ac on. It'll only get worse.
I4's are not perfectly balanced, so they vibrate. It is really only noticeable at idle. When the engine spins faster the vibrations aren't as noticeable, and the soft mounts help with that as well.
If you want a perfectly balanced engine, get a V6. Every power stroke has an opposite intake stroke to balance itself out. V6's also last a lot longer than an I4, or even a V8. One reason to spend a little extra. My mom's 11 year old Grand Caravan with 120,000 miles, 3.3L V6, idles smooth as glass. Much smoother than my brand new Forte! Gotta love those V6's!

Although, modern I4's are getting to the point where they don't degrade as fast, and stay balanced longer. So it's not as bad as it used to be. Still there though...

tyzall1584 · 06-22-2011, 12:17 PM

Quote:

Originally Posted by haydenks

I have the same condition on my 2010 SX. I've noticed that the a/c doesn't seem to affect either engine responsiveness or gas mileage when it's on.

Ditto on that. I think that my gas gets used up more when the windows and sunroof are open more than when I use the a/c. maybe thats because I tend to drive faster with the windows open

truraza · 06-22-2011, 12:44 PM

Two things are happening, an additional load at idle and the idle speed compensating for the load. Both of these conditions are why you feel the vibrations a little more than right at idle.

If you idle with no load and slowly accelerate; you'll notice a point where the car seems to vibrate a bit more and then go away.

All very normal.

elmerb · 06-22-2011, 01:00 PM

when I turn my A/C on....it's cooler

Smile and the whole world smiles at you. You cry and you cry alone.

n1ghtsh1ft · 06-23-2011, 01:21 AM

When my A/C is on, I don't notice the vibration at idle. I do notice the sound from my R exhuast is a little louder

haydenks · 06-23-2011, 06:57 AM

Quote:

Originally Posted by AutoItKing

Four bangers are notorious for vibrating at idle. Especially with the ac on. It'll only get worse.
I4's are not perfectly balanced, so they vibrate. It is really only noticeable at idle. When the engine spins faster the vibrations aren't as noticeable, and the soft mounts help with that as well.
If you want a perfectly balanced engine, get a V6. Every power stroke has an opposite intake stroke to balance itself out. V6's also last a lot longer than an I4, or even a V8. One reason to spend a little extra. My mom's 11 year old Grand Caravan with 120,000 miles, 3.3L V6, idles smooth as glass. Much smoother than my brand new Forte! Gotta love those V6's!

Although, modern I4's are getting to the point where they don't degrade as fast, and stay balanced longer. So it's not as bad as it used to be. Still there though...

Since V-6's aren't available in the Forte line, why even mention them? Remember, this is a Kia Forte Forum!!

AutoItKing · 06-23-2011, 10:51 AM

To make a point.

izzue · 06-30-2011, 09:57 PM

Well guys i swear when i turn the AC on i feel that the chair vibrates more. I am not sure if its normal. Got my car new but you know... factory defects sometime