Using air conditioning as additional descent brake

Hello!

I am wondering if anyone else came to the same idea as I have.
In other words, I am either genius or idiot, and I would like to confirm which one of those .

Everyone knows that using air conditioning increases fuel consumption, because the coolant compressor (when it's running) is mechanically connected/engaged to the engine, so it shares part of the mechanical power which the engine produces.
Therefore, I was thinking if the opposite effect would exist - when the car is going downhill and the engine is braking, would the air conditioning compressor utilize part of the braking power, or not.


So I tried my theory on a normal tarmac road which has a stable descent gradient which is several km long.
To shorten the story - I noticed that the car descends down approx 12% slower then I turn on air conditioning!

So, am I correct if I state that air conditioning does indeed "soak" a part of the kinetic energy which strains the engine and the transmission when it's braking downhill, or not?


Considering all this,

I was wondering if it would be wise to use air conditioning as a slight additional braking aid when performing steep offroad descents in 1st low gear?

Has anyone practiced this and how much effect does it give in real world?

Would this practice be harmful (in short terms or in long terms) to the coolant compressor, to the engine itself, or to other components (like the belt, etc.)?

:laugh: :laugh: :laugh:

Bosanek, are you a research student with too much time on your hands ?

after you publish your findings can you discover if the climate is changing because everyone's now got climate control.

Erm........ :blink: :whistle:

I think that when you select 4wd or low it overrides the ability to have the a/c on!

Obarno wrote: I think that when you select 4wd or low it overrides the ability to have the a/c on!

Think you're wrong

I should have prefixed my comment with for VVT vehicles. They have a little box situated above the throttle pedal which is the switch for the low range/ac.

IIRC, the pushbutton transfer box drops the aircon out when 4wd low is selected. Not sure why

Does the AC compressor run constantly when the AC is switched on? It doesn't in my Liana. It could cut out part way down a decent. It will provide a bit of breaking when running but I wouldn't rely on it.

It cuts in and out all the time. It makes as much difference in terms of power for climbing as it does for breaking on a descent. So you do notice when it cuts in.

Well I was on a holiday and I drove down the same descent every day in the morning for six consecutive days, so I had some time to study this question

Operation of the air conditioning system is not affected by the operation of electronic transfer case in my DDiS Jimny made in 2006, and vice versa. In other words, AC continues to work when I engage 4WD-L, and I can turn AC on or off during 4WD-L mode.

Wouldn't the compressor work all the time if the temperature knob is set to the coolest point and the fan blower strength is increased to at least level 3?

If you turn on all the lights and the wipers, then the alternator will also work harder and soak some more engine power.
In addition you could turn the engine off prior to the descent, to run the battery down a bit, before restarting.

_{Note. This is intended as a sarcastic reply and should be read as such.}

Another thing that can help is to decrease weight by for example expelling all the passengers from the vehicle before descending. That would make it much lighter, and by the laws of physics, less mass achieves less acceleration due to the force of gravity.