Omega Owners Forum

Chat Area => General Car Chat => Topic started by: EMD on 08 May 2016, 10:28:15

Title: A/C
Post by: EMD on 08 May 2016, 10:28:15
Reading another post i got the conclusion that air con
should be on all the time in winter and summer  :-\
And it saves you fuel ? How's that ? I thought air con put your fuel consumption
up  :-\
Wondering how many of you have your your a/c on all the time ?
Title: Re: A/C
Post by: Andy B on 08 May 2016, 10:45:29
Not sure where/why it should save you fuel .....  :-\

A/C is an extra load on the engine, but as it's a big lazy engine anyway, I'm sure it's hardly going to know that the a/c compressor is clutched in. The extra cost of running the a/c is negligible to over all running costs. NOT running the a/c will tnd to dry out seals on the compressor, so any costs saved will be spent on AN Other compressor.  :y

And opening a window/roof will alter the drag effect of the car enough that it'll use at least as much fuel as if you were running the a/c
Title: Re: A/C
Post by: Field Marshal Dr. Opti on 08 May 2016, 10:47:12
Not sure where/why it should save you fuel .....  :-\

A/C is an extra load on the engine, but as it's a big lazy engine anyway, I'm sure it's hardly going to know that the a/c compressor is clutched in. The extra cost of running the a/c is negligible to over all running costs. NOT running the a/c will tnd to dry out seals on the compressor, so any costs saved will be spent on AN Other compressor.  :y

And opening a window/roof will alter the drag effect of the car enough that it'll use at least as much fuel as if you were running the a/c

Sounds about right. :y
Title: Re: A/C
Post by: Terbs on 08 May 2016, 10:58:12
Hmmmmm...interesting....
I, like EMD, thought A/C sucked up the petrol :(

I can see the logic of Andy's reply :y
Title: Re: A/C
Post by: Andy B on 08 May 2016, 11:10:05
....
I, like EMD, thought A/C sucked up the petrol :(
 ....

I'm sure it has more of an effect on the 80 bhp of my Smart when it's on than it does on 200 bhp of an Omega ...... possibly whythe Smart's a/c has 1 & 2 settings  :-\
Title: Re: A/C
Post by: EMD on 08 May 2016, 11:53:37
Hmmmmm...interesting....
I, like EMD, thought A/C sucked up the petrol :(

I can see the logic of Andy's reply :y

Yep me too , so i will keep it on all the time now . When i have had the a/c on i dont think ive noticed any significant extra fuel usage so will monitor  ;) Its nice to have it on in this heat though  :y
Title: Re: A/C
Post by: Nick W on 08 May 2016, 12:05:06
I leave it at 20 degrees and auto during the summer and winter, but when the outside temp is between about 10 and 20(like now) I prefer the sunroof and window.


AC doesn't make any noticable difference on a decent sized engine, but it's hopeless on a small one: try it on a 1250 Fiesta on a steep hill!
Title: Re: A/C
Post by: BazaJT on 08 May 2016, 13:08:53
I did once see it somewhere that up to a certain speed[can't recall what] then the drag of having a window open was cheaper than having air con on and then above that speed the air con became the cheaper option.It used to be said that air con should be used at least once a week for a period of not less than 30mins,this stopped seals etc drying out and leaking,whether newer technology has made that idea redundant I don't know,when I had the XJ I never turned it off.Of course on the Omega it's never worked since I bought it!
Title: Re: A/C
Post by: Mr.OmegaMan on 08 May 2016, 15:09:10
A/C does help with the demisting also  :y
Title: Re: A/C
Post by: frostbite on 08 May 2016, 17:19:39
When I had my c280 when you pressed the EC button it turned the ac off but there was no noticeable gain or loss in fuel economy

And as said before if you've got 200+bhp you won't notice a difference
Title: Re: A/C
Post by: Steve B on 08 May 2016, 17:28:29
Mine is always on....

A little off topic...Do others find Driving a F/L omega saloon at 50mph with both rear windows down is very painful
Title: Re: A/C
Post by: frostbite on 08 May 2016, 18:15:01
Any care with the rear windows down booms like hell sort of thumping your ear drums
Title: Re: A/C
Post by: biggriffin on 08 May 2016, 19:04:13
Omega air-con is climate control, is on all the time unless the 'eco' button is on then the aircon is'nt working.,the amount of fuel used when on is not noticeable, on such a fuel efficient V6 :)
Title: Re: A/C
Post by: Shackeng on 08 May 2016, 19:35:54
Omega air-con is climate control, is on all the time unless the 'eco' button is on then the aircon is'nt working.,the amount of fuel used when on is not noticeable, on such a fuel efficient V6 :)

 :-\ :D
Title: Re: A/C
Post by: TheBoy on 08 May 2016, 19:53:06
My MV6 on petrol would average (over a few tanks) 24.8mpg with no AC and about 23.8ish with it on.

Keep it on, it'll be cheaper in the long run ;)
Title: Re: A/C
Post by: TheBoy on 08 May 2016, 19:54:00
Omega air-con is climate control, is on all the time unless the 'eco' button is on then the aircon is'nt working.,the amount of fuel used when on is not noticeable, on such a fuel efficient V6 :)

 :-\ :D
The 3.0 isn't too bad, but the 3.2 is bloody awful.
Title: Re: A/C
Post by: 05omegav6 on 08 May 2016, 20:13:05
Not sure where/why it should save you fuel .....  :-\

A/C is an extra load on the engine, but as it's a big lazy engine anyway, I'm sure it's hardly going to know that the a/c compressor is clutched in. The extra cost of running the a/c is negligible to over all running costs. NOT running the a/c will tnd to dry out seals on the compressor, so any costs saved will be spent on AN Other compressor.  :y

And opening a window/roof will alter the drag effect of the car enough that it'll use at least as much fuel as if you were running the a/c

Sounds about right. :y
Mythbusters tested this very thing... AC on/windows closed is the future... :y

But, at risk of repeating myself...

Please read the manual

Windows open, fan on to expel hot air from car, then windows closed and AC on to control temp... in case of Omega, temp to LO/16/17/18 etc to suit...

In winter AC on and temp to comfortable means nice toasty car and clear windows.

Basically leave aircon on... the engine ecu will turn it off/on as engine load dictates... far more efficient than manually switching it :y
Title: Re: A/C
Post by: TheBoy on 08 May 2016, 20:16:15
the ecu will turn it off/on as engine load dictates...
AFAIK on an Omega, only time climate disables a/c is if its under 4c outside
Title: Re: A/C
Post by: 05omegav6 on 08 May 2016, 20:19:37
the ecu will turn it off/on as engine load dictates...
AFAIK on an Omega, only time climate disables a/c is if its under 4c outside
Engine ECU over ruling Climate ECU to temporarily shut it down is what I meant ;)

WOT with an 1,800kg Pikey house on the back over the Alps might do it :y

Is all explained in the handbook ;)
Title: Re: A/C
Post by: omega2018 on 09 May 2016, 02:13:33
But, at risk of repeating myself...

Please read the manual

Windows open, fan on to expel hot air from car, then windows closed and AC on to control temp... in case of Omega, temp to LO/16/17/18 etc to suit...

In winter AC on and temp to comfortable means nice toasty car and clear windows.

Basically leave aircon on... the engine ecu will turn it off/on as engine load dictates... far more efficient than manually switching it :y

agree with harris on Please read the manual, shame he hasn't done it:

page 126:"When no cooling or drying is required press the ECO button to save fuel " ::)

the eco button switches off air con.
Title: Re: A/C
Post by: 05omegav6 on 09 May 2016, 03:18:12
ECO button only saves fuel if the windows/roof remain closed though...

Overall it is preferable to leave the aircon switched on ;)
Title: Re: A/C
Post by: Mr Gav on 09 May 2016, 22:43:25
Use it or lose it is the motto with aircon  ;)

AC doesn't make any noticable difference on a decent sized engine, but it's hopeless on a small one: try it on a 1250 Fiesta on a steep hill!

It`s ok on my 1300 Shitroen Nemo, though that is a devil`s juice engine
Title: Re: A/C
Post by: biggriffin on 10 May 2016, 11:01:39
But, at risk of repeating myself...

Please read the manual

Windows open, fan on to expel hot air from car, then windows closed and AC on to control temp... in case of Omega, temp to LO/16/17/18 etc to suit...

In winter AC on and temp to comfortable means nice toasty car and clear windows.

Basically leave aircon on... the engine ecu will turn it off/on as engine load dictates... far more efficient than manually switching it :y

agree with harris on Please read the manual, shame he hasn't done it:

page 126:"When no cooling or drying is required press the ECO button to save fuel " ::)

the eco button switches off air con.

Blimey kissed n made up. ;D
Title: Re: A/C
Post by: LC0112G on 10 May 2016, 11:21:11
A/C compressors are typically 3-5HP. So whilst cruising (using say 30-50HP to maintain speed) they are probably responsible for 10% of fuel used. However at WOT that drops to 2.5%.

The moral of the story is to increase the efficiency of the car whilst the A/C is on, drive everywhere as if you hair is on fire  ;D
Title: Re: A/C
Post by: TheBoy on 10 May 2016, 17:27:01
A/C compressors are typically 3-5HP. So whilst cruising (using say 30-50HP to maintain speed) they are probably responsible for 10% of fuel used. However at WOT that drops to 2.5%.

The moral of the story is to increase the efficiency of the car whilst the A/C is on, drive everywhere as if you hair is on fire  ;D
On my 3.0l auto, it was around 3-4% over several tankfuls. Insignificant really :)
Title: Re: A/C
Post by: Andy B on 10 May 2016, 19:44:44
A/C compressors are typically 3-5HP. So whilst cruising (using say 30-50HP to maintain speed) they are probably responsible for 10% of fuel used. However at WOT that drops to 2.5%.

The moral of the story is to increase the efficiency of the car whilst the A/C is on, drive everywhere as if you hair is on fire  ;D

I thought that the a/c was automatically turned off with WOT  :-\
Title: Re: A/C
Post by: 05omegav6 on 10 May 2016, 20:27:57
A/C compressors are typically 3-5HP. So whilst cruising (using say 30-50HP to maintain speed) they are probably responsible for 10% of fuel used. However at WOT that drops to 2.5%.

The moral of the story is to increase the efficiency of the car whilst the A/C is on, drive everywhere as if you hair is on fire  ;D

I thought that the a/c was automatically turned off with WOT  :-\
It is, as per tfm :D
Title: Re: A/C
Post by: Andy B on 10 May 2016, 21:51:11
A/C compressors are typically 3-5HP. So whilst cruising (using say 30-50HP to maintain speed) they are probably responsible for 10% of fuel used. However at WOT that drops to 2.5%.

The moral of the story is to increase the efficiency of the car whilst the A/C is on, drive everywhere as if you hair is on fire  ;D

I thought that the a/c was automatically turned off with WOT  :-\
It is, as per tfm :D
but who reads it?  ::)
Title: Re: A/C
Post by: LC0112G on 10 May 2016, 22:59:23
A/C compressors are typically 3-5HP. So whilst cruising (using say 30-50HP to maintain speed) they are probably responsible for 10% of fuel used. However at WOT that drops to 2.5%.

The moral of the story is to increase the efficiency of the car whilst the A/C is on, drive everywhere as if you hair is on fire  ;D

I thought that the a/c was automatically turned off with WOT  :-\

Exactly - improved fuel economy at WOT because the A/C is turned off. Result.  ;D
Title: Re: A/C
Post by: TheBoy on 11 May 2016, 08:05:27
A/C compressors are typically 3-5HP. So whilst cruising (using say 30-50HP to maintain speed) they are probably responsible for 10% of fuel used. However at WOT that drops to 2.5%.

The moral of the story is to increase the efficiency of the car whilst the A/C is on, drive everywhere as if you hair is on fire  ;D

I thought that the a/c was automatically turned off with WOT  :-\
And there was me thinking the Bullet's A/C wasn't working because it had a non A/C aux belt...   ...but its because its always at full bore ;D
Title: Re: A/C
Post by: Andy B on 11 May 2016, 08:27:28
.... 
 ...but its because its always at full bore ;D

 :y :y