hi,just bought a 2000 x v40,the problem is when i turn the aircon on the engine idles up and down (750 -1000rpm ) also i can feel a slight shudder on dash and gear lever .the car has done 160,000miles motorway miles ,it's got full volvo service history .when i drive everything is fine ,just staitionary and when i turn the aircon off it's run very smooth.is this normal for v40's.

Well, I don't know what to say, but I noticed the same thing about my V40 2001, only I sometimes have the feeling it also happens when driving and the aircon is full power. At least I don't think it's uncommon, but I don't know if it is "normal".
Regards, Stefan

This is a GUESS, but I would check your alternator - sounds like the engine can't get enough power to run the a/c...

tanks for reply ,i will look in to that and then see what happens ,maybe you might be right .cheers

Hi

I have a similar prob, but I haven't found a solution yet, so must apologise in advance for a rather useless reply.

Not sure about the alternator theory, I thought the compressor was run directly off the engine, not electric, and this is the major energy drain, sure it puts load on the engine, but the ECU should compensate and re-settle the tick over to the right range, for some reason it doesn't. This would tend to make me think that there is a faulty sensor, or an ECU prob, but I honestly don't know enough about it to make a reasonable diagnosis.

But, the point of my thread, if I do figure it out, I'll let you know.

Greg