Does air con really eat your fuel?

Mark_Hewitt

Pincher wrote: »

I was told if you don't run the air-con once a week, the bearings tend to seize up. Another problem is mold, which the condensation tends to wash away if you use it regularly.

It's also good to leave on in your car because as the A/C dries the air out, it keeps the inside of your car dry!

Exemplar

OK gang here's what I tried last night on my way home (NG9 4AH - Beeston, Nottingham - NG24 - Newark. Using A52 and back roads. 2004/04 Ford Focus 1.8 TDCi 115PS).

I tried driving with a blend of both front windows open in town then aircon on on faster stretches.

I found that, whilst it was ok with the windows down it was still warm air coming in plus fumes, so when i got to the A52 I put windows up and aircon on. Car settled to a nice temperature!! When I got to the back roads I dropped the windows and switched the aircon off, internal temperature rose again so had to put windows back up and put aircon on!

So after my extensive, exhaustive experiment i have realised that it's easier to drive with the aircon on if you want to remain at a nice temperature with no nasty whiffs/pongs/pollen!

I wonder if I can get some grant funding for this?

Gloomendoom

Of course, if you removed the air con system from your car it would make it considerably lighter and so wouldn't use as much fuel anyway.

While you're at it, you could remove all the 'essential' safety equipment, air bags, anti intrusion beams, thick pillars etc. and make you car lighter still. That way it would stop quicker and have better visibility so you would probably be able to avoid having the accident that you needed all the safety equipment for in the first place.



I'll get my coat.

only_mee

Nothing like being hot in the car then pressing the air con on and looking to the wife for where to hang my coat.

Seriously, will never own a car without it now.

Mark_Hewitt

only_mee wrote: »

Nothing like being hot in the car then pressing the air con on and looking to the wife for where to hang my coat.

Seriously, will never own a car without it now.

My wife was of that opinion. Oh you don't need A/C as long as you have a sun roof. Her latest car just happened to have it and she's never stopped using it!

I do wonder if many cars are sold without it these days? It's going the way of the CD player and ABS from an expensive optional extra to something that's included as standard.

Strider590

johnnyroper wrote: »

what a load of rubbish,even if the A/C on a car was electric motor the fuel consumption would be same if not worse than driving it via the ancilliary belt.
have you ever put on rear electric window and blower motor when at idle and noticed the load that is put on engine???

The rear electric window is different kettle of fish, they draw nearly 20 amps current!!! that's more than 240watts when the engine is running (battery voltage 13.8volts)!!
Short of the starter motor itself, the rear demister is probably the most high power device in any car and should never be left turned on for extended periods.
The reason that makes a difference is because your pushing the output capacity of the alternator, therefore having a negative effect on coil/spark voltage....

I simple low friction DC pump will use hardly any current at all!! and if you convert that DC into say 30v AC, to run a small AC motor (as in an EPAS unit), you can supply well in excess of 100 AC amps with no negative effects.

I must point out that I was the lead technical engineer on 2 EPAS projects in my previous employment........

Belt driven equipment is being driven by the crankshaft or camshaft, if you drove the wheels directly from the crankshaft they'd spin extremely quickly but you'd have practically no torque whatsoever.
Anything attached to this point is going to sap engine power and therefore efficiency will suffer....

Gloomendoom

You think a heated rear window takes more power than a typical car air conditioning pump?

The power necessary to operate a vehicle air-conditioning compressor is significant – it can be greater than the engine power required to move a mid-sized vehicle at a constant speed of 56 km/h (35 mph).

Source


Edit: And you still haven't explained where all this 'free' electricity comes from.
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cyclonebri1

alleycat` wrote: »

From the AA (doesn't say how they got the figure)

"The impact of using air con can pump up fuel consumption by up to 11% on slower roads."

I think up to a certain speed having the windows open is more economical (in drag terms) and over a certain speed aircon is more economical (with the windows closed) IYSWIM.

Both obviously cost you fuel in terms of either drag or power draw.

Perfect answer AC, it does, the argument is always by how much?

Paradigm

What about climate control? This uses a mixture of AC/ambient air/heater to maintain a specified temp...how do you work that out?

In my case I don't bother

cyclonebri1

Paradigm wrote: »

What about climate control? This uses a mixture of AC/ambient air/heater to maintain a specified temp...how do you work that out?

In my case I don't bother

I think you are right, too short a life and all that, ;)