Engine shudder with AC

uofmjock2 · Post by **uofmjock2** » 20 Aug 2010, 08:39

I have a 2002 Volvo s60 that has some slight shudders/surges when the AC is turned on during idle. It doesn't feel to me like it is wanting to stall It's not a constant shuddering, it may shudder once or twice and stops then does it again a few seconds later. It stops when I accelerate and returns when I stop at a traffic light. It happens at idle speeds in all gears. My engine idles at around 600 to 700 rpm with and without the AC on. Does anyone have a clue?

Retired MVS Contributor · Post by **Retired MVS Contributor** » 20 Aug 2010, 09:31

uofmjock2 wrote:I have a 2002 Volvo s60 that has some slight shudders/surges when the AC is turned on during idle. It doesn't feel to me like it is wanting to stall It's not a constant shuddering, it may shudder once or twice and stops then does it again a few seconds later. It stops when I accelerate and returns when I stop at a traffic light. It happens at idle speeds in all gears. My engine idles at around 600 to 700 rpm with and without the AC on. Does anyone have a clue?

Ifle is too slow, should be 750 to 800...Throttle body might need cleaning...

uofmjock2 · Post by **uofmjock2** » 20 Aug 2010, 15:25

I also noticed that the shuddering does not change the idle speed at all. Do you think it could still be the throttle body?

MelangeX3 · Post by **MelangeX3** » 23 Aug 2010, 06:11

I'm very curious about this too because I believe I have the exact same issue. I have a 2006 XC70 with 61k miles and the same symptoms. The turbo engine in the 06 has a really pronounced intermittent shudder with the AC on, which then goes away when AC is turned off. Idle speed on the tach does not move during vibrations. My 2001 non-Turbo V70 had an idle problem when one of the ignition coils went bad, but it felt different and had a constant idle fluctuation. I will try the throttle body cleaning and see if that helps.

Volvofix1 · Post by **Volvofix1** » 23 Aug 2010, 14:39

The first thing that I would do if the car was in our shop would be to recover and measure the a/c charge evacuate the system and leak test under vacum, then properly charge it with the correct amount of 134a. It sounds like the a/c may be cycling too much the idle control will adjust idle when a/c kicks in.

Dick K. from Fla.

endothrow · Post by **endothrow** » 05 Nov 2010, 09:21

I have the exact same problem on my car too. Not sure of the solution, but I chalked it up to the compressor adding load to the engine (S-belt), and the engine stuttering until it could adjust for the increased load. My idle is about the same with A/C on or off: 650-750rpms.