Fuel consumption, aircon on v off

Hi All

I know there are a few threads on here concerning fuel consumption, but I only twigged recently that my 06 Td4 turns on my air-con whenever I point the flow at the screen, but doesn't have the decency to tell me or let me override it!
So my starter for ten is has anyone compared their fuel consumption with the air-con switched on (whether by default or deliberately) and switched off?
I have tended to have the air to feet and screen, and wonder if this might be contributing to my slight drinking problem (as well as the much-discussed leaden foot!).

TIA


Ian

PS Thanks to all the contributors who alerted me to the air-con-auto-switch-on phenomenon. It does explain why my AC unit appeared to have an incontinence issue after parking, despite me not deliberately turning it on!

So my starter for ten is has anyone compared their fuel consumption with the air-con switched on

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am about to .. .. when i get a scangauge connected up ..

I have tended to have the air to feet and screen,

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same here

however .. if air speed allows .. i'll turn the fan 'off' .. 'n use the fresh-air-flow
which cuts out the a.c.

my theory is that it's the ptc heater in mine that's responsible ( mainly )
for the extra fuel consumption in winter temps ..
i've now temp. disabled it .. 'n keeping an eye on fuel consumption
( removed the relevant cab fuse box relay .. for now .. )

i reckon it should be possible to disable the a.c. / demist / heater-fan connection
although .. not looked into that possibilty yet ..

in summer i didn't notice any major difference in fuel consumption with the a.c. 'on'
nor did i notice much difference in engine power delivery

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btw: according to the techies .. the a.c. should be used at least once-a-week to keep the seals from drying out ..
'n the gas-charge from leaking out .. a depleted gas charge also evidently knackers the a.c. pump
be a case of circulating the lubricant that's mixed with the gas

My 2001 V6 doesn't seem to put the AC on in the demist setting. Is this only the later Freelanders that have that feature?

the later ones defintly have it whenever the position of the switch is on Screen only or screen and something else

today's scangauge report : ( TD4 engine )

fuel .. liters per hour at idle ..
a.c. off .. 0.54 lph
a.c. on .. 0.68 lph

~~~~~~~~~~~

*engine loading ..
a.c. off .. 17%
a.c. on .. 23%

* " This is a percentage of the max. power available currently being generated.
In some vehicles it is the max. available at the present rpm. "

I've been getting annoyed with this recently too.

Thinking of taking the centre console apart to try and disable the auto demisting switching. I'm hoping it's as simple as unplugging a wire.....

Yakko said:

I've been getting annoyed with this recently too.

Thinking of taking the centre console apart to try and disable the auto demisting switching. I'm hoping it's as simple as unplugging a wire.....

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I would suggest that you pull fuse #9 in the engine bay fusebox and then you'll find out how many times you need the AC to speedily demist the screen.

You'll possibly find that you need it more than you think.

I like it and would like to have this feature in my other vehicles.

What is it you don't like about this?

Singvogel. :cool2:

Agree with Singvogel, as I have no front screen heater or F B H I would be lost without the aircon. Heavens only knows how long it would take to demist your front screen without the automatic aircon. Running the engine for 15 minutes before you can drive off is not really an advisable option.

nickcc said:

Agree with Singvogel, as I have no front screen heater or F B H I would be lost without the aircon. Heavens only knows how long it would take to demist your front screen without the automatic aircon. Running the engine for 15 minutes before you can drive off is not really an advisable option.

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Pre-warming the engine is'nt an economical solution compared to using the AC. I wish mine had it but I have to press the snowflake button on mine to get AC assistance

I don't have a problem with it running, other than perhaps increasing fuel consumption through unintentional over-use. It's actually quite a good way of stopping us from forgetting to run the AC for 10 mins once a week to keep the system charged and lubricated.

Guides suggest using air con can increase fool consumption by up to 16%. But I would wonder if the is the worst case head line figure? An engine running at 2000 to 3000 revs produces loads of power. Turning the air con pump on in comparison is fek all. So fool consumption shouldn’t really change when moving.

IanSG19 said:

I don't have a problem with it running, other than perhaps increasing fuel consumption through unintentional over-use. It's actually quite a good way of stopping us from forgetting to run the AC for 10 mins once a week to keep the system charged and lubricated.

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Mine doesn't work at the moment as the car sat engine-less for 6 months
I must get round to getting my recharge kit out.

From Hd3's scangauge data (whatever that may be!), it looks as the litre per hour burn rate at idle could be as much as 20% lower with the AC off, so the 16% figure you cite isn't unknown. How this translates into mpg at 2500rpm I don't know!

IanSG19 said:

From Hd3's scangauge data (whatever that may be!), it looks as the litre per hour burn rate at idle could be as much as 20% lower with the AC off, so the 16% figure you cite isn't unknown. How this translates into mpg at 2500rpm I don't know!

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From a percentage point of view the AC does make a big difference while the engine is idling as an idling engine is only very lightly loaded. If the same test was carried out while the engine is pulling the car along the extra load imparted by the AC compressor is almost nothing as a percentage.

scangauge data (whatever that may be!)

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be one of these :

Welcome to Scangauge Homepage - www.scangauge2.co.uk ( English Version )

be a couple of hippo riders on these pages have them ..
maybe more that a couple for all i know

useful device for sure ) .. and lite enough to attach to the dashboard with 'bluetack' if needed ..
mine's just below the car's gauges ..

~~~

From a percentage point of view the AC does make a big difference while the engine is idling as an idling engine is only very lightly loaded. If the same test was carried out while the engine is pulling the car along the extra load imparted by the AC compressor is almost nothing as a percentage.

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makes sense

thing about the scangauge is that it updates the reading every couple of secs.
and certain readings fluctuate quite a bit.
not so great to read ( some ) .. whilst one is trying to keep eyes-on-road ..

i did the test at idle simply out of curiosity .. only had the gauge connected since yesterday ..

anyhowz .. ..

will edit this post in a minute 'n add PTC 'on' liters per hour reading

( i did an average liters-per-mile test today .. ac 'on' / ac 'off ..
( should have written it down .. have shut it down now ..
( will do some other time ..

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edited to add ..

the PTC on/off at idle .. worked out similar to ac on/off
i.e. :
fuel .. liters per hour at idle .. ( aprox due to gauge fluctuations .. i used the middle reading between hi 'n low )
ptc off .. 0.54 lph
ptc. on .. 0.68 lph

ptc + ac .. 0.72 lph

with PTC only .. 'on' .. the idle raises from 780 to 851
and i know from sitting in neutral .. and raising rpm to 2k .. that .. the PTC on/off will effect part throttle as well
and also .. with PTC 'on' .. the hippo will have a tad better acceleration response from a standing/rolling start from lights/roundabouts ..
hence i'm reckoning an average liter-per-mile test might show the ptc to be the higher fuel burner ..

will try an average fuel consumption .. via the scangauge .. with ac ( and maybe ptc ) on .. and off ..
problem be .. to be accurate .. i'd need a few runs .. in the same direction .. on the same road ..
on a day when there's no wind .. and the the ambient temp would be constant ..

don't hold ye collective breath

hd3 said:

be one of these :

Welcome to Scangauge Homepage - www.scangauge2.co.uk ( English Version )

be a couple of hippo riders on these pages have them ..
maybe more that a couple for all i know

useful device for sure ) .. and lite enough to attach to the dashboard with 'bluetack' if needed ..
mine's just below the car's gauges ..

~~~



makes sense

thing about the scangauge is that it updates the reading every couple of secs.
and certain readings fluctuate quite a bit.
not so great to read ( some ) .. whilst one is trying to keep eyes-on-road ..

i did the test at idle simply out of curiosity .. only had the gauge connected since yesterday ..

anyhowz .. ..

will edit this post in a minute 'n add PTC 'on' liters per hour reading

( i did an average liters-per-mile test today .. ac 'on' / ac 'off ..
( should have written it down .. have shut it down now ..
( will do some other time ..

Click to expand...

You can do the same test as the AC test at idle but instead of putting on the AC, switch on the heated rear window and blower on max blowing to the floor. This will load the alternator instead of the AC compressor but the results will show much the same as running the AC but we don't think twice about putting on electric items

You can do the same test as the AC test at idle but instead of putting on the AC switch on the heated rear window and blower on max blowing to the floor. This will load the alternator instead of the AC but the results will show much the same as running the AC

Click to expand...

true

was trying a bit of that today .. watching alternator output ..
and liters-per-hour .. maybe should have tried the 'engine-load' gauge as well
( didn't think of it )

but we don't think twice about putting on electric items

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i try to .. .. rear window heater stay 'off' ( rain-x anti fog works just fine ) ..
fan mainly only used on setting '1' .. ( will use '2' temporarily if a fast in-cab warm up is needed )
will use fresh air-flow instead of fan if possible ..
electric seat-heaters stay disconnected ..
( personal preference .. didn't like the electric-heated-vests from motorcycle days
( and part of my crap-back-help system .. involves synthetic fleece seat covers and memory-foam padding ..
ptc currently disabled by removing the in-cab relay ..
( looking to add a seperate switch for that .. '
( 'n maybe a seperate switch for each of the 3 elements .. although maybe that's a bit OTT

hd3 said:

true

was trying a bit of that today .. watching alternator output ..
and liters-per-hour .. maybe should have tried the 'engine-load' gauge as well
( didn't think of it )


i try to .. .. rear window heater stay 'off' ( rain-x anti fog works just fine ) ..
fan mainly only used on setting '1' .. ( will use '2' temporarily if a fast in-cab warm up is needed )
will use fresh air-flow instead of fan if possible ..
electric seat-heaters stay disconnected ..
( personal preference .. didn't like the electric-heated-vests from motorcycle days
( and part of my crap-back-help system .. involves synthetic fleece seat covers and memory-foam padding ..
ptc currently disabled by removing the in-cab relay ..
( looking to add a seperate switch for that .. '
( 'n maybe a seperate switch for each of the 3 elements .. although maybe that's a bit OTT

Click to expand...

The more fuel the car uses the less effect switching things on makes. My V6 does 24 mpg on my daily commute of 10 miles in summer. In winter with the seat on the blower on and whatever else I need it does drop my mpg but by something like 1 mpg which i'm more than happy to live with if it keeps me comfortable!!

Singvogel said:

What is it you don't like about this?

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Don't get me wrong, I love AC, I'd just like to be able to turn it off and still have air blowing at the screen.

My FL is currently leak free, so isn't really suffering from condensation, plus there's the heated front screen. It'd be nice to be able to have the air blowing at the screen while I drive without needlessly running the AC.

My V6 does 24 mpg on my daily commute of 10 miles in summer. In winter with the seat on the blower on and whatever else I need it does drop my mpg but by something like 1 mpg which i'm more than happy to live with if it keeps me comfortable!!

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i've been tring to figure out why .. in recent freezing winter temps ..
i went from 40+ mpg .. down to 33 mpg .. (td4)
( usual distance of 20 to 30 miles .. or more )

maybe it's not the ac/demist or the ptc ?
can't think of anything else off hand .. haven't changed driving habits ..
tyre pressures checked weekly .. brakes are not dragging ..
engine's running fine as has been ( knock knock on wood

maybe it's the engine and drive train oils 'time-to-warm-up' ..
plus added load via ac/demist and electronics ?

only different habit .. was using both the ac/demist plus the ptc heater ..
( and that ptc heater causes the ecu to add more fuel by default ..
( it must .. if the idle-above.idle rpm raise automaticly when it's switched on
( plus the engine acceleration is positively effected
( but over what engine rpm range .. or other factor range .. is unknown to moi
( the ac .. or any other added electrical load .. don't effect the idle rpm

can only really try a proper test .. maybe with running constantly at peak torque rpm ..
as much as is possible ( that's 50mph in 5th gear ) .. and switching things on and off ..
in constant ambient weather conditions .. etc etc ..

might be a waste of time .. and fuel .. all-in-all

'n i don't know how accurate the average-fuel-use is .. on that gauge ..
only time will tell ..

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It'd be nice to be able to have the air blowing at the screen while I drive without needlessly running the AC.

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looking at the electrics diagrams and explanations ..
i Suspect the fan-dial a.c. microswitch could be disconnected ..
still leaving the main ac console switch operative .. with 'demist' if wanted
( not a zillion% sure though .. without re-reading thru the info ..
i.e.
http://macassemble.com/lrm/freelander/Freelander Electrical Library (2004).pdf
and ..
http://macassemble.com/lrm/freelander/Freelander Electrical Circuits (2002).pdf