Need ideas: A/C ON - car jerks

[uros]

Hi everybody!

Sorry for my english since it is not my native language.
I'm having troubles with my car jerking when the A/C is on. So far I have taken it to the dealership, plug it to the computer and have the whole A/C inspected but no errors found.
I tried to figure it out when exactly car jerks and came to this findings. When I turn A/C on it works fine - it is cooling, the compressor cycles and car works fine for about 30 miles. And then car suddenly jerk once (like compressor would be hard to cycle ON). After that jerk it is only the matter of time when car will jerk again. Intervals between jerking are getting shorter. Meanwhile the A/C is cooling perfectly! But if I turn the A/C off, the jerking is gone as well.
So my guess would be there is something wrong with my A/C - but why no one finds any problem with it? Everytime I'm haveing my car at the mechanic everythings works fine and it looks like I am making it all up!
Any ideas?

BYe!

[donald7150]

the A/C compressor is driven directly by the engine
it is said that the compressor can use up to 8 horsepower to run it
i feel the same bump sometimes in my '97 neon. but its not that bad

maybe your compressor is sticking a little

[uros]

Thanks for the answer. Anyway I know it is normal to feel slight bump somethimes when compressor turns on and those bumps don't bother me at all - you can bearly feel them. But from time to time there is real brutal bump (it almost feels like if you would have a manual and try to jump start your wehicle - when you release your clutch while the car is moving with the engine off. - such bump is really horrible if it happens during driving).