Air-con: recommended min usage to keep in good order.

yes point taken. Bleach is a bit harsh but spraying it in moderation should be ok you tend to find that some cars are more prone than others for bacterial odor but usualy ready to use bleaches like the fragranced ones are well diluted as they are made for disenfecting kitchen worktops which are usually wiped with foam type sponge .
Dont use raw bleach like domestos

Also you tend to find that vehicles that have this problen will nearly allways be prone for it luckily it doesent happen to them all.

Although last autum i purchased deoderising spray cans again just to see if they have improved think i did 2 or 3 vehicles with them havent herd any complaints yet.

 

Have had different aircon'd cars for the last 20 yrs or so. Always had the aircon running constantly, summer and winter. Never had any ill effects (kept cars for about 6 yrs) and keeps the interior dry and condensation free.

Fuel consumption not really an issue if you know how to use your right-foot properly.

 

"Fuel consumption not really an issue if you know how to use your right-foot properly "

You obviously pay no attention to fuel consumption.

 

To be honest, I'm pretty anal about recording fuel fillups and keeping an eye on my fuel consumption and I've never really been able to see a discernible difference. I'm sure it DOES make a small difference, but I don't see my cars using more fuel in summer than winter. I think the longer cold-start periods, extra use of lights, wipers etc in winter probably use up as much fuel as the aircon does in summer. "Worst case" aircon use tends to be urban delivery driving with loads of stopping and starting combined with opening and closing the door a lot (letting warm air back into the car). In most "ordinary" cars, at typical motorway speeds, I think it would be perfectly possible to more than recover the additional fuel consumption of an aircon system simply by driving a couple of MPH slower.

 

Sorry to be pessimistic but you seem intent on not believing any of the info or experience of anyone who disagrees with you. As previously mentioned - why not try switching your own air-con on when your ambient temp is high enough and see for yourself?

 

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Certainly nothing can argue with that logic.....I wonder if the recent switch to electric power steering pumps was similarly inspired and maybe A/C systems will go the same way eventually.
I'm testing my A1 with the system off and on to see if there's any difference.
John

 

There's a new type of A/C coming in the next couple of years. I'm not sure exactly how it's going to work yet, maybe somebody can enlighten me.
http://www.tiffe.eu/

 

Do you have any figures to suggest otherwise, Mointainwalker? I've outlined my experiences of it, on several cars. Whist it is, of course, obvious that a compressor drawing a few kilowatts of power is obviously going to require extra fuel to run it, it's (on average) a very small percentage of the total amount of power required to move a car from A to B.

 

Yes, it's all to do with power management. The manufacturers are under pressure to reduce CO2 emissions (bit fines from the European Commission if they don't!) and maximise fuel economy (consumer pressure). Engine-driven power steering isn't that efficient because the pump needs to be sized so that it can deliver full flow when the engine is idling (where most manoeuvring is done and demand is highest), and that means they're turning WAY too fast when the engine is running at more normal driving speeds, just "wasting" the pressure through the relief valve and back to the reservoir. The electric steering pumps can deliver flow (when needed) irrespective of engine speed. The same is true of water pumps (with the added advantage that you can then run the water pump with the engine off and stay warm in the car for 15 minutes or so.

I think the big problem with aircon is that the demands on the alternator from all these other electrically-driven systems that used to be mechanical. For a while now, manufacturers have been wondering about going to 24 or even 48 volt electrical systems because the cabling required to deliver this much power at 12V is really heavy. The problem is that there's just SO much 12V stuff around!

Electric vehicles obviously have electrically driven aircon pumps, so it must be possible, it's just a question of whether it's the most efficient way of doing it on conventionally-engined vehicles.

How were you going to do the tests on you Audi? In the past, I've found setting the trip computer to display instantaneous MPG and watching the figure as you switch on the AC to be not very accurate. Too many things change too easily on the road. Also, when first switched on, the pump will run continuously until the anti-icing feature kicks-in and switches it off. In this weather, that could be less than a minute! All I can suggest is that you find a bit of constant-speed motorway and zero the average consumption display, then drive (say) 20 miles with the aircon on, followed by (ideally) the same 20 miles in the same direction with it switched off and see if you can get a difference in average consumption. On top of that, you'd really need to be able to repeat it 3 times and get consistent differences each time, but it's a hell of a task without the controlled environment of a rolling road emissions lab. Part of the problem (especially in this weather) is that the differences you'd be looking for would be less (I reckon!) than the accuracy of the trip computer.

 

To be absolutely honest, I really couldn't give a toss about the fuel consumption on the Audi.....I use it when I need to, and drive it as I see fit. Its computer says 52.4 mpg, and on a long run this goes up to 53.2......I thought I'd give it a try on two days, each on a 100 mile run.
With air con, 52.4. Without air con, 52.4 Whatever power its using (according to the on board computer) it aint much.
John

 

1 day whilst servicing tractor air con at dealers garage it was connected to the horsepower testing dyno thing.
After i was finished we started up the tractor which had horse power of 136 once the magnetic compressor clutch kicked in the power droped to 130.
That was on a hot day 15*c ambiant temp the system worked on cycles of on for 30- 50 seconds off for 20 seconds.
But every vechicle is different.
The argument of the amount of extra fuel consumed will never be solved

 

John, was your 100 mile trip a recent one? In this weather, I wouldn't expect the aircon to be doing much at all!

Although it's true multiplexing has reduced cable size, you still need big cables for high current draw stuff (like electric power steering pumps). The thing electric vehicles have in their favour is that their traction batteries are usually several hundred volts, so they can use a higher voltage from the traction battery to power things like aircon pumps.

6kW sounds like a lot for an aircon pump. The trouble is though, it's almost impossible (unless you're in a lab) to isolate the other sources of power drain. The cycling in and out sounds reasonable though.