[neoto]

Did anyone notice any shudder (or slight hesitation) when driving uphill at ~100 km/h (2000 rpm in 6th gear) and AC on? It's 2011 i30cw CRDi with 90 HP.
It's quite annoying in my i30 as this is almost always happening in these conditions. If the AC is off, all fine. Driving on the straight or downhill, all fine. Driving faster/slower, all fine...
We have a piece of the highway going uphill for a few kilometers with the speed limited to 100 km/h - so I can't really avoid it by driving faster/slower.

[accim]

Yes. I notice it also on my 116hp CRDi, especially when the temp's are above 30°C as they were few days ago.

But that hesitation is noticeable on most cars under 200hp. But I notice it also in 3rd, 4th, 5th gear. You can feel like the car suddenly looses approx 15hp? I notice that also on my fathers Santa Fe 2.2 CRDi, mom's Volvo V40.. But maybe we are not talking about the same thing.

[Phil №❶]

Yes. I notice it also on my 116hp CRDi, especially when the temp's are above 30°C as they were few days ago.

But that hesitation is noticeable on most cars under 200hp. But I notice it also in 3rd, 4th, 5th gear. You can feel like the car suddenly looses approx 15hp? I notice that also on my fathers Santa Fe 2.2 CRDi, mom's Volvo V40.. But maybe we are not talking about the same thing.

I remember reading from an old Ford workshop manual of 1970's vintage that the ford air conditioner compressor compresses 4 tons of refrigerant / per minute. There's just no way to have that type of energy consumed and not feel the effects in the engine. Modern petrol engines are built with light flywheels which enables quick acceleration, but reduced angular momentum, so any loads, hills, towing, air cond, all have an immediate effect. The diesel engine is less prone to these effects due to a heavier flywheel, but the diesels in our I30 are a very small capacity motor. Having said that, it doesn't happen in the auto.

[neoto]

i30 has some advanced trickery with throttle and A/C in order to compensate for the lost power, but this shudder might really be the AC compressor kicking in.

accim, it really feels like it lost a few horse power for a second and then it's back to normal. However, I did not really notice it on other cars, but it might be that I was not paying enough attention...