Air Con On or off?

Ebe_Scrooge

mobileron said:

its climate control so do i presume it uses fuel while heating the car

Actually, heating the car uses no additional fuel (assuming we're talking about an ordinary petrol/diesel engine).  When you switch the heating on, all it does is divert the hot water from the engine cooling system through the heater matrix to heat the car - so it's heat that is otherwise wasted, the engine is generating the heat whether you like it or not

OK, to be super-pedantic - if you switch on the heater fan to blow the warm air into the car, then that uses electricity, which costs extra fuel.  But the amount of electricity - and therefore fuel - to run a small fan really is so negligible as to be immaterial.  You'd need some super-sensitive equipment to be able to measure the extra load added by just the fan.

Car_54

Ebe_Scrooge said:

mobileron said:

its climate control so do i presume it uses fuel while heating the car

Actually, heating the car uses no additional fuel (assuming we're talking about an ordinary petrol/diesel engine).  When you switch the heating on, all it does is divert the hot water from the engine cooling system through the heater matrix to heat the car - so it's heat that is otherwise wasted, the engine is generating the heat whether you like it or not

OK, to be super-pedantic - if you switch on the heater fan to blow the warm air into the car, then that uses electricity, which costs extra fuel.  But the amount of electricity - and therefore fuel - to run a small fan really is so negligible as to be immaterial.  You'd need some super-sensitive equipment to be able to measure the extra load added by just the fan.

Just an ammeter, Shirley? Then you can calculate the power used from W=VI.

iwb100

You should leave it on always. That’s what most car manuals will recommend. The system is designed to be on. In many cars it is actually climate control so basically is about bringing the car to temperature and it’s designed to be on most of the time. 

JustAnotherSaver

As I track my MPG on every fill up

The difference it makes in MPG consumption is barely noticeable.

I'm sure someone will come in & say it dropped their 40MPG down to 10MPG but from my experience if I was going to get that worried about the difference it makes (again, from MY experience) then I'd probably just not bother driving a car because that costs more to me than flicking an A/C switch on or not.

sk2402005

The amount of additional fuel used will depend hugely dependign on the car.

In my experience a diesel engine is much more suited and will use less than a petrol engine, presumably due to the much higher torque available from a diesel compared to a petrol engine.

also a larger engine will be less noticable than a small engine.

Ditzy_Mitzy

On, off, makes no difference to me as it doesn't work and the belt has been cut off.  Air conditioning off, generally, to save the electricity needed to illuminate a now completely useless telltale.  

Richard53

I had a Mondeo with climate control for ~7 years and 70k miles. I kept a record of every litre of fuel I put in against mileage. I kept the a/c on permanently (as recommended in the vehicle handbook) and never had to regas or do anything else to it. I did experiment with turning it off a few times, just from curiosity. I couldn't see any difference between driving with it on or off, so any effect was less than the normal variation between tankfuls - I would guess less than 1 mpg. Whatever, it was well worth it for the benefit of having clean, dry air in the cab for 12 months of the year.

mobileron

Have had climate control for over30 years on many cars always left on as handbook told me.If you turn it off the cost of seal replacements will cost more than any fuel saved, Bet everyone has it turned on at the moment.

Brewer21

As above really, had a new car in 2014 and the aircon is never switched off even in winter. Its just set to auto (climate control) and the temp set for summer/winter to suit

Never a problem, never re gassed works a treat. As for using more fuel, it's negligible.