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I have a 2016 limited outback delivered 2/2016. Loved it the first year- everything seemed great. Starting in late winter, at any stop, the car would tremor as if it was going to stall even though RPM's never wavered. Fast forward to warm weather and I noticed that anytime I accelerated, the A/C blows warm air until I finish the acceleration. I took it in for the 24k service and was told they installed some update to fix the tremoring at idle and that the A/C issue was just how it is because of fuel efficiency -A/C system is ok per the dealer. Still having the same issues and just put 2 and 2 together and realized that the tremoring at idle stops when the A/C is turned off. Is this normal?!? Thanks for any advice!
 

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Older Outbacks used an air conditioning compressor with a clutch on it, and when the clutch kicked in (or released) there would be an easy-to-notice vibration or sound etc.

2010 and later Outbacks use a new variable-displacement compressor. There is no clutch; they're always on. They can smoothly and (almost) silently change how hard they pump based on orders from the computer.

The computer is set to be opportunistic- when you get on the throttle, the computer will deliberately slack off the A/C to give a more responsive acceleration. As soon as you back off, the computer ramps up the A/C to catch up on pressure needed for climate control.

The idle on any engine can get choppy if it drops too low. The engine computer learns its idle settings by monitoring itself in a feedback loop. If conditions change over the months and years, the learned idle may be too low, and the extra load from the air conditioning might be enough to drag it down to where you get extra vibration.

I'm guessing they just forced it to start a new learning cycle.
 

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I have a 2016 limited outback delivered 2/2016. Loved it the first year- everything seemed great. Starting in late winter, at any stop, the car would tremor as if it was going to stall even though RPM's never wavered. Fast forward to warm weather and I noticed that anytime I accelerated, the A/C blows warm air until I finish the acceleration. I took it in for the 24k service and was told they installed some update to fix the tremoring at idle and that the A/C issue was just how it is because of fuel efficiency -A/C system is ok per the dealer. Still having the same issues and just put 2 and 2 together and realized that the tremoring at idle stops when the A/C is turned off. Is this normal?!? Thanks for any advice!
Have you looked at your brake booster. While vehicle is at normal running temp, put car in drive with ac on and applying brake. Monitor rpms, before and after, while applying PARKING brake and releasing foot brake. My rpms went from 600 to 800 and running smooth. I still need to see if it’s check valve or booster.
will let you know
 

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(formerly) 03 H6 OBW , (presently) 06 WRX Sportwagon & 2021 Honda CR-V
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Have you looked at your brake booster. While vehicle is at normal running temp, put car in drive with ac on and applying brake. Monitor rpms, before and after, while applying PARKING brake and releasing foot brake. My rpms went from 600 to 800 and running smooth. I still need to see if it’s check valve or booster.
will let you know
2 year old post, probably been dealt with already.
 
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