Register Login
The UK's No.1 Chrysler Owners Forum
Reply
 
Thread Tools
Old 1 Week Ago   #31
Moderator
Join Date: Mar 2010
Location: Dorset
Posts: 7,299
Thanks: 767
Trader Rating: 0
United Kingdom 
Re: Aircon light

Quote Originally Posted by AndyRKett View Post
An 8.1 litre V8 SUV and a 4.6 litre V8 sedan..... definitely a direct comparison to a 1.2 litre 2015ish fiat 500.....

I LOL too !!
In percentage terms, the 500 will likely be worse then the SUV.

Quote Originally Posted by AndyRKett View Post
in 2004
The sun's power hasn't changed much since 2004. The amount of heat you need to remove to keep the car cool in summer hasn't changed much either.
__________________


"Just 'cos you're not paranoid, doesn't mean they're not out to get you"

jrkitching is offline Reply With Quote Quote 
Old 1 Week Ago   #32
Join Date: May 2011
Location: Norfolk UK
Posts: 7,883
Thanks: 351
Blog Entries: 8
Trader Rating: 0
United Kingdom 
Aircon light

Quote Originally Posted by jrkitching View Post
In percentage terms, the 500 will likely be worse then the SUV.



The sun's power hasn't changed much since 2004. The amount of heat you need to remove to keep the car cool in summer hasn't changed much either.


Back in 2004 and not forgetting we are talking about V8 engines at 8.1 litres and 4.6 litres, people buying these cars and the time period, where not concerned about gas mileage. They are big vehicles requiring a lot of energy to cool, they are likely built with all the aerodynamic properties of a barn and all the technological prowess of a coal fired power station.

Verses a new little car where fuel economy is a high priority, technology has moved on with more advanced technology. Smaller cabin and much more aerodynamic little car, yes there will be a huge difference between the cars in this very old study and a current day little fiat.

No need to carefully engineer and match components for best all round usability, we'll just fit the biggest aircon compressor we can find to cool down our road barge and the engine will have plenty of power to turn it over.
__________________
For all my Punto and Punto Grande Instructional Videos Visit My YouTube page
MyNew Website is now at www.puntohowto.com
Or check out the Facebook Punto page

Last edited by AndyRKett; 1 Week Ago at 10:48.
AndyRKett is offline Reply With Quote Quote 
Old 1 Week Ago   #33
It's always more involved
Join Date: Feb 2016
Location: Tynemouth
Posts: 1,505
Thanks: 55
Trader Rating: 0
John202020 has donated!
United Kingdom 
Quote Originally Posted by AndyRKett View Post
Smaller cabin and much more aerodynamic little car, yes there will be a huge difference between the cars.
Are cars AS aerodynamic now, as say the early 90's ? Where everything was totally flush with the body ( like no door handles sticking out or wipers that sat below the bonnet line) headlights that were sealed to the bonnet edge raked screens and rounded corners, and 0.3 drag coefficient was a selling point? Can't help feel modern cars are not as slippery as older ones?
__________________
FIAT Forum Useful Links:
Donate to FF | Buy FF Merchandise | Classifieds | FF Insurance | How-to Guides


Last edited by John202020; 1 Week Ago at 11:09.
John202020 is offline Reply With Quote Quote 
Old 1 Week Ago   #34
Moderator
Join Date: Mar 2010
Location: Dorset
Posts: 7,299
Thanks: 767
Trader Rating: 0
United Kingdom 
Re: Aircon light

Quote Originally Posted by John202020 View Post
Are cars AS aerodynamic now, as say the early 90's ? Where everything was totally flush with the body ( like no door handles sticking out or wipers that sat below the bonnet line) headlights that were sealed to the bonnet edge raked screens and rounded corners, and 0.3 drag coefficient was a selling point? Can't help feel modern cars are not as slippery as older ones?
The 500 isn't particularly aerodynamic; IIRC the drag coefficient is about 0.36, which is why fuel economy drops substantially once you go over about 55mph. It was designed as a city car, after all.

The best of the modern motorway cruisers will have a Cd of around 0.25. This is a few years old now, but still relevant.
__________________


"Just 'cos you're not paranoid, doesn't mean they're not out to get you"


Last edited by jrkitching; 1 Week Ago at 12:00.
jrkitching is offline Reply With Quote Quote 
Old 1 Week Ago   #35
Join Date: May 2011
Location: Norfolk UK
Posts: 7,883
Thanks: 351
Blog Entries: 8
Trader Rating: 0
United Kingdom 
Aircon light

Quote Originally Posted by John202020 View Post
Are cars AS aerodynamic now, as say the early 90's ? Where everything was totally flush with the body ( like no door handles sticking out or wipers that sat below the bonnet line) headlights that were sealed to the bonnet edge raked screens and rounded corners, and 0.3 drag coefficient was a selling point? Can't help feel modern cars are not as slippery as older ones?


We'll early 1990s cars we're still left over bricks from the 1980s, the likes of the panda, uno and tipo are prime examples of that, later cars like the punto where more aerodynamic but these were not really 'early 90s' cars and were more late 90s,

However what we are talking about In relation to the above article is a early 2000s car, more specifically an 8.1 litre SUV which looks something like this

Click image for larger version

Name:	IMG_9695.JPG
Views:	12
Size:	187.3 KB
ID:	182395


It's probably worth noting that the design of these cars also relates back to the 80s and even 70s without any major update to the shape and aerodynamics. Just for comparison here is a 70s version

Click image for larger version

Name:	IMG_9696.JPG
Views:	12
Size:	275.8 KB
ID:	182396

This is not an aerodynamic car as cars go, parachutes have a slightly better aerodynamic coefficient. Opening the window on a car like this is never going to improve or worsen its aerodynamic properties and therefore you'll be unlikely to see any significant deterioration in fuel economy windows up or down.

It is however so large that it will require an industrial air conditioning unit to make even the slightest dent on the ambient interior temperature.

Basically the one study people are quoting to try and prove their rule, has no more basis in this discussion than the colour of the sky or the latest pop group to come out of South Korea. A huge 2004 America SUV is not a small efficient European hatchback made much later.
Likes John202020, Mick F, g8rpi liked this post
__________________
For all my Punto and Punto Grande Instructional Videos Visit My YouTube page
MyNew Website is now at www.puntohowto.com
Or check out the Facebook Punto page

Last edited by AndyRKett; 1 Week Ago at 12:15.
AndyRKett is offline Reply With Quote Quote 
Old 1 Week Ago   #36
UFI
500 TwinAir Plus
 
UFI's Avatar
Join Date: Jan 2013
Posts: 1,470
Thanks: 75
Trader Rating: 0
UFI has donated!
Australia 
Re: Aircon light

The 500 has a very primitive A/C, it's 90's tech - doubly so for the manual system, the 500 is based on a 2003 Panda, not that different to the tech you'd find in a mid 00's American.

The 500 has a CD of 0.36, pretty much line ball with the 0.38 of a Tahoe or Suburban. Even on a CdA basis, it's clear that the 8.2 will have power to spare over that poor little 1.2. You can't tell aerodynamics by looking, a Jaguar E-Type is as aerodynamic as a Jeep Wrangler. Today's mid-large vans are in the 0.31 range - just a box on wheels.

The interior volume of a 'full size' US sedan is not that dis-similar to a 500.




The main difference is the 4.6 will barely feel the drain of an A/C compressor. My 4.0 sure doesn't.


If you've got a 1.2 (not a MJ or TA) or possibly a 1.4, try this, turn the A/C on in say 3rd at 1500rpm and floor the throttle. Slow down and try again in with the A/C off. That's how much power an A/C compressor saps when it's working.

It's like night and day. Some cars (and the TA is one of them) will compensate for A/C usage by changing the throttle mapping, so you can't tell if the A/C is on or off, but the extra drain is still there.

A/C automatically cycles on and off so no idea how that's different for growing bugs vs turning it off yourself? My Renault completely ignores the A/C button and won't run the A/C if the selected temp is above ambient - to the point where on a wet day I have to turn the temp way down and freeze if I want it for demisting.

I suspect that you guys think you have the A/C on when in reality all you've got is that light on the dash.

Also, we all know petrol cars are more efficient in hot weather. Diesel engines might like cold air, but even then you're loosing out on longer warm ups, thicker fluids, denser air molecules, generally increased electrical loads and drag from wet roads.

Here's more from SAE:

http://articles.sae.org/12053/

Strangely, I can't find a single piece of evidence that A/C makes no measurable difference as is often suggested on various forums.

If you can drive consistently, you can pick up pretty small things:



The slight dip (from a linear progression) in May is because I tried running without the DPF cleaner - looks like I lost 1mpg from that.
__________________
2012 Fiat 500 Twinair+ 2016 Renault Trafic dCi140 LWB 2009 Proton Arena 2005 Jeep Wrangler 2005 Toyota Prius 1989 Nissan Skyline 1949 Ford F1 255 V8

Last edited by UFI; 1 Week Ago at 12:43.
UFI is online now Reply With Quote Quote 
Old 1 Week Ago   #37
Join Date: Sep 2010
Location: Athens, Greece
Posts: 4,131
Thanks: 78
Trader Rating: 0
Greece 
Re: Aircon light

Quote Originally Posted by UFI View Post
The 500 has a very primitive A/C, it's 90's tech - doubly so for the manual system.

The 500 has a CD of 0.36, pretty much line ball with the 0.38 of a Tahoe or Suburban. Even on a CdA basis, it's clear that the 8.2 will have power to spare over that poor little 1.2.

The interior volume of a 'full size' US sedan is not that dis-similar to a 500.

http://4.bp.blogspot.com/-BsIMeGPnaS...oic-2%2560.jpg

If you've got a 1.2 (not a MJ or TA) or possibly a 1.4, try this, turn the A/C on in say 3rd at 1500rpm and floor the throttle. Slow down and try again in with the A/C off. That's how much power an A/C compressor saps when it's working.

It's like night and day. Some cars (and the TA is one of them) will compensate for A/C usage by changing the throttle mapping, so you can't tell if the A/C is on or off, but the extra drain is still there.

A/C automatically cycles on and off so no idea how that's different for growing bugs vs turning it off yourself? My Renault completely ignores the A/C button and won't run the A/C if the selected temp is above ambient - to the point where on a wet day I have to turn the temp way down and freeze if I want it for demisting.

I suspect that you guys think you have the A/C on when in reality all you've got is that light on the dash.

Also, we all know petrol cars are more efficient in hot weather. Diesel engines might like cold air, but even then you're loosing out on longer warm ups, thicker fluids, denser air molecules, generally increased electrical loads and drag from wet roads.

Here's more from SAE:

http://articles.sae.org/12053/

Strangely, I can't find a single piece of evidence that A/C makes no measurable difference as is often suggested on various forums.
With the 1.4, if you turn off ac and let the car go down the hill at 50 kmh in 3rd or 4th, the car slows down much quicker with AC on , it's like you hardly need to press the brake to slow down!

Consequently, with the increased load you have to use the throttle much more than with it off, i estimate 0.5l/100 km easily with the AC at power setting 2, and a good 1.0l/100 km with the AC on full blast
__________________
ahmett is offline Reply With Quote Quote 
Old 1 Week Ago   #38
Moderator
 
g8rpi's Avatar
Join Date: Nov 2013
Location: Cambridge
Posts: 2,218
Thanks: 169
Trader Rating: 0
g8rpi has donated!
United Kingdom 
Re: Aircon light

Quote Originally Posted by AndyRKett View Post


<SNIP>

You can't compare an electric car air con compressor, it requires a dedicated motor just to spin the compressor and keep it going without any other outside forces acting upon it. So all the time the aircon is on, the motor needs to be running and burning fuel, it's not practical to keep switching a motor on and off so the system will be balanced to operate constantly with the motor giving a set speed.

<SNIP>

This is not correct. Modern motor driven AC compressors (not just car ones) use brushless DC motors with electronic control. True they run all the time AC is required, but they run just fast enough to provide the cooling required. Much more efficient than turning a big compressor (motor or engine driven) on and off system losses are lower at lower speeds. Some electrics have heat pumps that give you 3kW of heat for less than 1kW of electricity in winter and cooling in summer.


Note that climate control is normally more efficient than plain AC, the system has more control and does a better job than most humans can.
I never notice the climate control coming on in terms of performance, driving a Croma with a 150hp mJTD helps and overall consumption is in the ballpark of what some 500 and Panda owners are reporting. big engine driven gently can have advantages over a small engine being driven hard to keep up with real life traffic conditions.
Apart from aerodynamics, open windows cause other issues with noise (bad low frequency resonance on a lot of cars) distraction, pollution and safety.

Robert G8RPI.
__________________
FIAT Forum Useful Links:
Donate to FF | Buy FF Merchandise | Classifieds | FF Insurance | How-to Guides

g8rpi is offline Reply With Quote Quote 
Old 1 Week Ago   #39
Join Date: May 2011
Location: Norfolk UK
Posts: 7,883
Thanks: 351
Blog Entries: 8
Trader Rating: 0
United Kingdom 
Re: Aircon light

Quote Originally Posted by UFI View Post
The 500 has a very primitive A/C, it's 90's tech - doubly so for the manual system, the 500 is based on a 2003 Panda, not that different to the tech you'd find in a mid 00's American.

The 500 has a CD of 0.36, pretty much line ball with the 0.38 of a Tahoe or Suburban. Even on a CdA basis,


If you've got a 1.2 (not a MJ or TA) or possibly a 1.4, try this, turn the A/C on in say 3rd at 1500rpm and floor the throttle. Slow down and try again in with the A/C off. That's how much power an A/C compressor saps when it's working.

Just to address these three points.

The basics of air conditioning means that climate control or not, it will generally use the same compressor, evaporator, condenser and expansion valve, these are the main components that decide how efficiently the system will work, I know from direct experience that older cars have more Heath Robinson set ups with oversized compressors, more flexible rubber hosing and huge evaporators or undersized condensers. So no matter how primitive you think the systems in modern cars, are they are much more efficient these days as the components are designed to all work together.

The surburban above has a Cd of 0.45 so a long way off what you're suggesting, further more the drag coefficient does not directly relate to what we are talking about here nor the energy needed to move through the air. A Boing 747 has a much lower Cd than a fiat 500 but I can guarantee that when moving at 30mph the 747 will have a lot more surface area and therefore air, pushing back against it.

The Cd is not a simple way of comparing one vehicle to another, unless you've got a degree in fluid dynamics, and you want to factor in all the other variables.

Finally if you put any car in any gear and floor it with the aircon off, and with the air con on, there should be no noticeable difference between the two as cars are designed to kill the AC at wide open throttle to give maximum power to the engine, as long as your foot is buried in the carpet, you won't have aircon.

This argument is getting silly now, trying to compare a massive V8 to a small fiat 500 is like chalk and cheese. Basically the research done above is nonsense in modern, normal European cars.
Likes Mick F liked this post
__________________
For all my Punto and Punto Grande Instructional Videos Visit My YouTube page
MyNew Website is now at www.puntohowto.com
Or check out the Facebook Punto page
AndyRKett is offline Reply With Quote Quote 
Old 1 Week Ago   #40
Happy Chappy
 
Mick F's Avatar
Join Date: Nov 2014
Location: Tamar Valley, Cornwall
Posts: 1,395
Thanks: 50
Trader Rating: 0
Mick F has donated!
United Kingdom 
Re: Aircon light

Quote Originally Posted by jrkitching View Post
Some folks just don't want to hear the truth.
I agree.

I agree that the more the load on it, the more it effects the fuel consumption. It's obvious, isn't it. I don't think anyone is arguing with this fact.

The experiment linked up thread, had the ambient temp at 24degC .......... a rather warm and rare summer's day here in Cornwall.

I said up thread, that we rarely ever have the AirCon set at the extreme ends. Generally, it's set in the 500TA at 20degC ................. so it's hardly going to affect the fuel consumption at all.

Mick.
__________________
FIAT Forum Useful Links:
Donate to FF | Buy FF Merchandise | Classifieds | FF Insurance | How-to Guides

Mick F is offline Reply With Quote Quote 
Old 1 Week Ago   #41
UFI
500 TwinAir Plus
 
UFI's Avatar
Join Date: Jan 2013
Posts: 1,470
Thanks: 75
Trader Rating: 0
UFI has donated!
Australia 
Re: Aircon light

Quote Originally Posted by AndyRKett View Post
However what we are talking about In relation to the above article is a early 2000s car, more specifically an 8.1 litre SUV which looks something like this

Attachment 182395


It's probably worth noting that the design of these cars also relates back to the 80s and even 70s without any major update to the shape and aerodynamics. Just for comparison here is a 70s version

Attachment 182396
There's a thing aerodynamicists talk about called detail optimization. Those two look little alike aerodynamically. Somewhat ironically I could say exactly the same thing about the 60's 500 vs today's.

Fact remains the tech on a suburban released in 2000 is about the same as that on a Panda in 2003, hardly 'much newer'.

Quote Originally Posted by AndyRKett View Post
Finally if you put any car in any gear and floor it with the aircon off, and with the air con on, there should be no noticeable difference between the two as cars are designed to kill the AC at wide open throttle to give maximum power to the engine, as long as your foot is buried in the carpet, you won't have aircon.
I don't think you've ever driven a car, or at least not a 4 cyl. The vast majority of cars I've driven don't do this. My TA does, my Trafic does, but the Suzuki, Proton, Nissan, Mercedes, VW, Jeep & Renault don't/ didn't.

I don't know where your figures are from, but wikipedia lists the 2006 Tahoe Hybrid at .038, a Tahoe is a short Suburban. All else being equal, the better fineness ratio of a Suburban should help it over a Tahoe. Nothing short of a Jeep Wrangler (completely flat windscreen, massive flat grill, massive tyre flares) has a Cd of 0.45. You have to go well back into the 70's to find anything like that.

I already addressed CdA. The CdA of a Suburban is about double of a 500, but it's engine nearly 7 times larger, no wonder the A/C barely made a difference to it's economy, a bit of load just means it's operating in at a higher BMEP.

Fact remains, there's not a single paper any where that claims A/C usage is too small a factor to consider or measure. Fact remains the sedans tested showed similar results.

My previous Renault was rated 9.7 city, it returned 6.7 over the 20K that I had it, and that includes trailer towing. My lifetime average speed as recorded by my GPS was 26km/h- dead on for the NEDC city number. How far over NEDC are you averaging with your A/C always on?

The only possible point of debate is what speed is the cross speed in A/C on vs windows down. Only a few internet experts claim otherwise.

And I'd argue that the 500, basically a 2003 car (and it takes about three years to go into production), isn't really as modern as you'd have me believe. Most of your arguments might have some weight on a diesel S Class or something, but they almost have no relation to a 500.

You know, sedans showed similar results, so why bang on about the SUV???
__________________
2012 Fiat 500 Twinair+ 2016 Renault Trafic dCi140 LWB 2009 Proton Arena 2005 Jeep Wrangler 2005 Toyota Prius 1989 Nissan Skyline 1949 Ford F1 255 V8

Last edited by UFI; 1 Week Ago at 15:00.
UFI is online now Reply With Quote Quote 
Old 1 Week Ago   #42
UFI
500 TwinAir Plus
 
UFI's Avatar
Join Date: Jan 2013
Posts: 1,470
Thanks: 75
Trader Rating: 0
UFI has donated!
Australia 
Re: Aircon light

Quote Originally Posted by Mick F View Post
I said up thread, that we rarely ever have the AirCon set at the extreme ends. Generally, it's set in the 500TA at 20degC ................. so it's hardly going to affect the fuel consumption at all.
20 is pretty low. The lowest my Renault goes is 18 for comparison.

There's certainly logic to this, but away goes the idea that it keeps the system 'healthy'. The A/C is going to spend a lot of it's time off.
__________________
2012 Fiat 500 Twinair+ 2016 Renault Trafic dCi140 LWB 2009 Proton Arena 2005 Jeep Wrangler 2005 Toyota Prius 1989 Nissan Skyline 1949 Ford F1 255 V8
UFI is online now Reply With Quote Quote 
Old 1 Week Ago   #43
UFI
500 TwinAir Plus
 
UFI's Avatar
Join Date: Jan 2013
Posts: 1,470
Thanks: 75
Trader Rating: 0
UFI has donated!
Australia 
Re: Aircon light

Quote Originally Posted by TrevC View Post
. By coincidence Mick I ran a 2003 Clio for 9 years (with my daughter) and when she sold it the aircon was still blowing cold and was never re-gassed.
My Jeep is 12 years old, only gets used every six months and still on it's original charge. And I can tell you a matte black roof (with no head liner) on a black Jeep on a 44*C day in the middle of no where, I'd know if the A/C wasn't still close to 100%.

I suspect the argument of seals drying out might have applied to cars so fitted in the 60's. It doesn't seem like you'll come out ahead running the A/C to save the seals in a modern car.
__________________
2012 Fiat 500 Twinair+ 2016 Renault Trafic dCi140 LWB 2009 Proton Arena 2005 Jeep Wrangler 2005 Toyota Prius 1989 Nissan Skyline 1949 Ford F1 255 V8
UFI is online now Reply With Quote Quote 
Old 1 Week Ago   #44
Moderator
Join Date: Mar 2010
Location: Dorset
Posts: 7,299
Thanks: 767
Trader Rating: 0
United Kingdom 
Re: Aircon light

Quote Originally Posted by Mick F View Post
The experiment linked up thread, had the ambient temp at 24degC .......... a rather warm and rare summer's day here in Cornwall.
On a sunny day when the ambient temperature is 24C, the temperature inside the car will be about 45C.

That's why there are so many warnings about leaving dogs and children in cars in summer.
__________________


"Just 'cos you're not paranoid, doesn't mean they're not out to get you"

jrkitching is offline Reply With Quote Quote 
Old 1 Week Ago   #45
Happy Chappy
 
Mick F's Avatar
Join Date: Nov 2014
Location: Tamar Valley, Cornwall
Posts: 1,395
Thanks: 50
Trader Rating: 0
Mick F has donated!
United Kingdom 
Re: Aircon light

Quote Originally Posted by jrkitching View Post
On a sunny day when the ambient temperature is 24C, the temperature inside the car will be about 45C.

That's why there are so many warnings about leaving dogs and children in cars in summer.
It's static sunshine that makes the difference. Radiation vs conduction.

When the car has no windchill when stationary, you could well be correct in 24degC sunshine having 45degC inside - not tested this fact yet - but as soon as the car is whizzing along, the temp would decrease to ambient or thereabouts.

Biggest load on AirCon is in slow moving traffic or when stationary combined with direct hot sunshine. Small loads are normal because we rarely have direct hot sunshine here.

Someone correct me if I'm wrong here please.
AirCon works by chilling the air to remove the moisture. The car's ventilation system then mixes it with warm air to a greater or lesser degree from the heater matrix to get the desired temperature. You would then suppose that the chiller is constantly running and fixed, but it's not. The more the demand, the more air needs to be chilled, but it's on a thermostat so when not in high demand, it cycles.
As I say, correct me if I'm wrong.

Regards,
Mick.
__________________
FIAT Forum Useful Links:
Donate to FF | Buy FF Merchandise | Classifieds | FF Insurance | How-to Guides

Mick F is offline Reply With Quote Quote 
Reply
Currently Active Users Viewing This Thread: 1 (0 members and 1 guests)
 
Thread Tools

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off

Forum Jump
Similar Threads
Thread Thread Starter Forum Replies Last Post
(T) aircon vs non aircon alternator shell switching flisko Punto (Mk2/2b) 11 24-05-2016 11:24
Had AirCon now No AirCon what belt do i use tomo187 Lets Talk FIAT 0 09-08-2010 13:40
(T) Stilo JTD. No aircon light. DMarsden Stilo 10 24-05-2008 17:33
difference between aircon and non aircon on the mk1 hgt donny lad FIAT Boo Archives 1 22-07-2007 18:18
(T) Aircon HornetUK Punto (Mk2/2b) 2 02-04-2005 23:02