Whenever the ac compressor engages, the car jerks

[Anton CH.]

This problem first started when the car would jerk if you haven't turned the ac in a while. So on a hot day you turn on the ac and it would jerk once and then engages, disengages will be smooth for a week. Now the car jerks a little on the freeway or street roads whenever the ac compressor engages.

[Jeff N.]

Mine's the same - any compressor experts out there? Clutch problem or ??

[Anton CH.]

So do you still use the AC and ignore the problem?

[PhilipJCaputo]

My 95 530i does a similar thing, but it really isn't noticable to anyone else in the car but me. While I'm driving with the AC on, I can feel each time the AC engages and dis-engages. I've also noticed that the instant mpg indicator drops down a few mpgs when I feel AC compressor kick in.

To me it isn't a big deal untill passengers feel the AC compressor turn on and off.

[Jeff N.]

...on my wife's 2000 Honda CR-V, her A/C system is completely transparent to the driver. You can't tell when it kicks in or kicks out. Can't even really feel the drag on the engine when it's running. And it's small 4 cylinder car.

I don't know if this due to a newer A/C design that is more efficient and engages better or if it's age on our cars...

Calling some A/C experts.. :)

Jeff

[ryan roopnarine]

my compressor was replaced about 7 years ago and it still makes my tranny hunt like nobody's business when the ac and cruise control are simultaneously engaged.

[Warren N.CA]

My assumption is the compressor clutch is tired due to old age, and will eventually die (same as all of us). For now, I have bigger fish to fry and have no trouble ignoring this minor glitch.



My 95 530i does a similar thing, but it really isn't noticable to anyone else in the car but me. While I'm driving with the AC on, I can feel each time the AC engages and dis-engages. I've also noticed that the instant mpg indicator drops down a few mpgs when I feel AC compressor kick in.

To me it isn't a big deal untill passengers feel the AC compressor turn on and off.

[632 Regal]

its part of the package, if you dont like it dont use the AC...:D

[PhilipJCaputo]

its part of the package, if you dont like it dont use the AC...:D

Soon as I drop the girlfriend off, I usually kill the AC and drop the windows, just to get an extra pony or two! ;)

[jplacson]

smaller cars also need smaller compressors. I'm running a small 520i (M20) and I don't feel the A/C kick in as much... feels just like a small 'tap' on the gas pedal.

[Bill R.]

low side... some of the early preludes had a 12000 btu unit... pretty small compared to most american or european cars... The low tonnage means less horsepower requirements so its not felt as much.. that and I think that the crv has a variable displacement compressor so that it can start up almost unloaded and increase displacement as needed.... It should be in that factory manual that i sent you :)...






...on my wife's 2000 Honda CR-V, her A/C system is completely transparent to the driver. You can't tell when it kicks in or kicks out. Can't even really feel the drag on the engine when it's running. And it's small 4 cylinder car.

I don't know if this due to a newer A/C design that is more efficient and engages better or if it's age on our cars...

Calling some A/C experts.. :)

Jeff

[Jeff N.]

.. a couple things.

- the BMW compressor is a whopper relative to the engine size vs some cars
- the BMW compressor is not a variable displacement. Variable displacement is a newer style of compressor that minimizes the impact of the clutch/release effect of the unit.

I suspect that the second item is likely more the root cause. Just got back from Cali and had an 04 Chevy Impala as a rental car. Not bad really - had the GM 3.8 V6 and a 4 speed slushbox. Interior was well thought out and it drove pretty nice. Makes me believe that the american's can sorta of build an OK car when they want. (Now how it will hold up in 15 years...who knows!). But, I digress.

The effect of the A/C cutting and in out on the car was nil just like our little honda at home. The impala is similar to the 535 in cabin size and engine size and so I suspect it has similar a/c cooling requirements. That and the Americans never seem to skimp on the A/C.

Soo...it was my guess that there is something new going in the later model a/c units just as you've mentioned.

PS - I still need to get my DVD reader drive. Grr. Waiting till I upgrade the entire PC which is overdue. No time to setup a new pc..oh well. :)



low side... some of the early preludes had a 12000 btu unit... pretty small compared to most american or european cars... The low tonnage means less horsepower requirements so its not felt as much.. that and I think that the crv has a variable displacement compressor so that it can start up almost unloaded and increase displacement as needed.... It should be in that factory manual that i sent you :)...

[Bill R.]

way as the car cools down it can reduce the displacement of the compressor and reduce the horsepower needed to turn it..., the startup is just another benefit of it.




.. a couple things.

- the BMW compressor is a whopper relative to the engine size vs some cars
- the BMW compressor is not a variable displacement. Variable displacement is a newer style of compressor that minimizes the impact of the clutch/release effect of the unit.

I suspect that the second item is likely more the root cause. Just got back from Cali and had an 04 Chevy Impala as a rental car. Not bad really - had the GM 3.8 V6 and a 4 speed slushbox. Interior was well thought out and it drove pretty nice. Makes me believe that the american's can sorta of build an OK car when they want. (Now how it will hold up in 15 years...who knows!). But, I digress.

The effect of the A/C cutting and in out on the car was nil just like our little honda at home. The impala is similar to the 535 in cabin size and engine size and so I suspect it has similar a/c cooling requirements. That and the Americans never seem to skimp on the A/C.

Soo...it was my guess that there is something new going in the later model a/c units just as you've mentioned.

PS - I still need to get my DVD reader drive. Grr. Waiting till I upgrade the entire PC which is overdue. No time to setup a new pc..oh well. :)

[Jeff N.]

.

[Anton CH.]

So moral of the story, it is normal on our cars. Just makes me wonder why I have never noticed it before.