Hi Everyone,

Have a question related to engine deceleration when changing gears.

I have a 2010 A4 2.0T Quattro Manual with Sports Package. I noticed yesterday that when the air conditioner is turned on and in a certain setting (front blast), the engine decelerates faster than usual when changing gears from first to second and subsequently from second to third.

I tried changing the air conditioner setting (floor only, up only, etc), and noticed a difference between certain settings. Still the fact remains that when using a certain air conditioner setting, the engine decelerates faster (and since I wasn't used to the engine decelerating RMPs THAT fast, causing some head-booping *rockout*).

Anyway, wondering if this is something that I should be concerned about or if this is due to the extra load on the engine since the AC is on.

When turning off the AC, the engine reacts and decelerates more like what I'm used to.

Thanks!

(Tried searching this topic and couldn't find anything so my apologies if its been posted anywhere on this site)

 

As with any car, the AC takes A LOT of power. It's basically extra friction in the belts that the engine has to overcome. I have a Little Ford Escort, and ohh dear god! I have to turn the AC off for hills, otherwise I have to floor it. The results are instant when switching between AC on and off. The AC causes drag on the engine, so it will slow down faster. Now whether or not the drag on your engine is excessive is the question.

 

consider the air conditioning compressor like a dead cylinder in the engine. It is compressing refrigerant to cool down the air passing through the evaporator.

 

Understood. Makes sense.

I think that is the question- whether the deceleration is excessive or not. I think I'll have to find out in due time as I get to learn more about this specific car.

Thanks for chiming in.