Engine speed & air conditioning

[anotherMickG]

Hi All,

Got a 51 plate Diesel Almera. Can I ask everyone with a similar car...

Does your engine speed up significantly when you turn on the Air Con ?

I know that in some cars the engine speed does increase because of the extra juice needed, but it seems a bit excessive on this car ! So much that the steering wheel shakes !!!!

One garage told me that it might e that the battery isn't holding its charge as well as it should ??? but I'm not so sure about that.

Any thoughts anyone ??

 

[rlees85]

normally speeds up by about 100 maybe 200 (At the very most) RPM at idle. thats on a petrol though.

 

[sri_alan]

could be the clutch on the AC unit not engaging the pulley properly and jamming it? not sure how it could jam it, maybe the AC is faulty but you get the idea. that would make it harder to turn and mean more work for the engine

 

[dan_bourne]

my engine speed goes up breifly as the torque used to get the compressor working is engaging... but it goes back down...

 

[tla-gti]

With mine when the A/C button is pushed the revs rise a little and you can hear the extra load on the engine, but then the revs drop back down to tickover after afew seconds.

 

[Veero]

Yeah it will increase with the A/C. When you turned mine on you could definately hear it labouring a bit, revs would increase by about 150-200 ish and stay higher until you switched it off.

Not sure why the battery not charging would affect the engine revs with the A/C on, the extra juice should come straight from the alternator, hence the extra revs and increased load on the engine.