The car in question is a 2005 Sonata with 2.7L V6 and 4-speed auto. When the AC is on, often when at a red light, the car will suddenly push against the brakes as if the transmission were trying to lock up. It will be sitting there at an idle and all the sudden there will be a sudden jerk as it tries to start moving.
It's not strong enough that it actually causes the car to move, but the idle seems to drop a bit when it happens. The car drives and shifts fine, and the transmission fluid looks normal.
Anyone have an idea where to start?
Thanks!
Hyundai Sonata Transmission "Catches" when A/C on
- Thread starter NilsonCain
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A guess, the ac compressor is turning on and the car has to raise the idle to overcome the extra load giving you the feeling that its taking off.
John
Originally Posted By: Ojustracing
A guess, the ac compressor is turning on and the car has to raise the idle to overcome the extra load giving you the feeling that its taking off.
John
It has gotten much more noticable over the past several months, and become more of a hard jerk...
Certainly not something it used to do, and not like other vehicles.
Originally Posted By: NilsonCain
It has gotten much more noticable over the past several months, and become more of a hard jerk...
Certainly not something it used to do, and not like other vehicles.
maybe its time for a compressor recharge and some fresh PAG oil. When was the last recharge?
Compressor or AC system has not been serviced since we owned the car. It was bought used with 12,000 miles so I doubt it was before then.
I can try recharging the system and adding some oil to see if it helps... Thanks
Be very careful with the oil level; too much and it will affect the cooling. Happened to me on a Corvette I owned years ago. Added " a little extra" to help lube the compressor and the it got all the way to the expansion valve/ capillary tube assy and cut the cooling in half.
Found out Chevy recommends, when replacing a compressor, to measure the oil amount coming out of the old one and add only that to the new one.
May not apply to a Hyundai tho.....
I'm not sure if that engine has iacv but if it does clean it. that should help. but a little jerk is normal, because the engine has to increase the idle to keep up with the load given off from the a/c compressor.
i agree with ojustracing
Alright guys, I'm going to buy one of the AC recharge kits that includes oil and change out the refrigerant... Is there any more environment-friendly way to do so other than dumping the old 134a into the air?
Also I'd like to clean the IACV while Im at it... where would I locate that on this car? I have service manuals for my 'Yotas but no clue where that would be on the Sonata.
Thanks for the help folks.
My old '04 Elantra A/T would do the same thing.
I'm fairly confident it's not a broken motor mount... my thinking was the torque convertor was attempting to lock up, but I hope re-doing the AC system will help. Anyone help me locate the IACV?
Thanks!
Got to the Hyundai service site. It has all the OEM stuff on it. http://www.hmaservice.com/
Use IE and enable popups.
user name gencoupe
password gencoupe
awesome! thanks
The Hyundai site tells me that it's an incorrect username/password
They must have disabled it. You can sign up for free though.
And there is a Canadian site too. http://www.haccservice.com/Welcome.aspx
I figured out where the IACV was and cleaned it and the MAF. MAF looked fine but the IACV had a lot of carbon buildup inside. The AC system was a bit low and I topped it off with r134 with leak seal and oil.
The symptom still exists but seems like it's much less now. We'll see how it progresses.
Seems like the symptoms are just as bad again... Had the AC on and put it in reverse from a parking space and the car bogged down and was jerky, like if you were to try and start off in a manual without enough throttle.
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