Kia Forte Forum banner
1 - 20 of 21 Posts

·
Registered
Joined
·
21 Posts
Discussion Starter · #1 ·
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.
 

·
Registered
Joined
·
459 Posts
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.
 

·
Registered
Joined
·
59 Posts
When I turn my AC on my rpm goes up like 500, and its a tad louder
 

·
Registered
Joined
·
1,804 Posts
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.
 

·
Registered
Joined
·
78 Posts
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.
 

·
Registered
Joined
·
346 Posts
Shakes under the seat? :confused: Do you mean it idles a little rougher?
 

·
Registered
Joined
·
1,987 Posts
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...
 

·
Registered
Joined
·
543 Posts
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 :D
 

·
Registered
Joined
·
100 Posts
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.
 

·
Registered
Joined
·
72 Posts
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
 

·
Registered
Joined
·
78 Posts
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!!:rolleyes:
 

·
Registered
Joined
·
1,987 Posts
To make a point.
 

·
Registered
Joined
·
21 Posts
Discussion Starter · #15 ·
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
 

·
Registered
Joined
·
543 Posts
Maybe because its cold. I get cold and shiver when the a/c is on sometimes too haha. In all seriousness, I think the seats vibrate more than most other cars anyway. When I am idling I can literally see the chair shaking, with or without a/c
 

·
Registered
Joined
·
1,987 Posts
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
It's normal. The A/C compressor adds load to the engine, and to keep the RPMs the same, the ECU dumps more fuel. And hence the extra vibration. Pretty much every small engine will do it. Not very noticeable with big engines since they have more power/momentum.
 

·
Registered
Joined
·
142 Posts
It's normal. The A/C compressor adds load to the engine, and to keep the RPMs the same, the ECU dumps more fuel. And hence the extra vibration. Pretty much every small engine will do it. Not very noticeable with big engines since they have more power/momentum.
HI ALL ,1.6 forte 2010 sx ,i have no vibration on car seat
i only have this squizing sound and clarking sound ,no hisitaion at all.
 

·
Registered
Joined
·
21 Posts
Discussion Starter · #19 ·
I think I should note that it is not only when the AC is on. As soon as you turn on the fan the vibration can be noticed.

After all reading all your comments i believe it is quite normal
 

·
Registered
Joined
·
48 Posts
First post ever! I am so excited.... I noticed the vibration after turning on the AC for the first time on my 2011 SX Koup with 4200 miles while sitting at a traffic light... it super annoying but I still love my car
 
1 - 20 of 21 Posts
Top