General How's the air con in the Panda?

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General How's the air con in the Panda?

Great debate gentlemen, most informative.

One comment raised my eyebrow....a 1.2 car of 20 years ago with aircon...
Could you imagine an Opel Corsa 1.2 or Fiesta and even dont even think about a first gen Panda with aircon? I'd struggle to get it off up my street with it turned on!
My VOLVO V40 is 15 years old and I DO notice a loss in power when leaving the house and taking the 5km climb uphill. So would assume the extra gas required would translate into more fuel consumed. When the pump switches in and out to pressurise the aircon system is noticeable too, however much less so on the Panda. I am assuming the ECU of the FIAT IS intelligent enough to read the ambient conditions and requirements and adjust accordingly.
My truck has intelligent sensing in that when full power is required (hill climbing) certain power zapping circuits are switched off provided it is safe to do so and only come back in when the throttle is lifted or if needed reducing pumping losses and un necessary alternator charging loads and therefore improving fuel consumption.
 
I'm confused - am I the only one. What I know is that my previous 100HP had climate control on permanently, except when I turned it off to see if the mpg changed. It didn't by a noticeable amount. Likewise the aircon in my current 4x4 TA - no significant difference.

The lower the output of the engine or driving economically then the difference will be greater. Before I got the aircon regassed on my 177bhp Rover 75 my average fuel consumption was 20mpg after it was sorted and the following year it dropped to 19 mpg. The lower power engine will quite clearly be working harder.
 
My VOLVO V40 is 15 years old and I DO notice a loss in power when leaving the house and taking the 5km climb uphill. So would assume the extra gas required would translate into more fuel consumed. When the pump switches in and out to pressurise the aircon system is noticeable too, however much less so on the Panda. I am assuming the ECU of the FIAT IS intelligent enough to read the ambient conditions and requirements and adjust accordingly.
My truck has intelligent sensing in that when full power is required (hill climbing) certain power zapping circuits are switched off provided it is safe to do so and only come back in when the throttle is lifted or if needed reducing pumping losses and un necessary alternator charging loads and therefore improving fuel consumption.

A modern ECU can compensate for the additional load by injecting more fuel when the compressor kicks in; this takes away the noticeable power loss you could feel with first generation systems (unless you're already demanding full power from the engine). You don't notice the additional power drain so much, (because the engine automatically compensates), but it's still there, and the impact on fuel economy is much the same.

The additional fuel still has to be accounted for; intelligent sensing can maximise the power when you most need it, but the total energy needed (which directly equates to fuel use) has to be made up later. For example, you can reduce the instant consumption by temporarily disengaging the alternator, but it'll have to work harder when you reengage it to recharge the battery, and that will burn the fuel you saved in the first place.

What will save fuel are systems which make use of energy which would otherwise be wasted; regenerative braking being one obvious example.
 
I'm confused - am I the only one. What I know is that my previous 100HP had climate control on permanently, except when I turned it off to see if the mpg changed. It didn't by a noticeable amount. Likewise the aircon in my current 4x4 TA - no significant difference.


That's more about how difficult it is to measure even a 10% change in economy in the short term. Also most folks would be understandably reluctant to drive around with the A/C off and the windows shut for the time needed to get a reasonable measurement in the current UK weather!


The easiest way to see the difference without special equipment is to use the trip computer when you're cruising at constant speed on a level motorway on a long journey.
 
I'll leave this here, I think. There's no point in presenting good science to someone who isn't listening with an open mind.
It’s not good science, it’s an open access journal, and a paper written by someone with a gmail account based in India... and it’s one paper with one case study that you’re using to try and prove a rule across all cars of all makes and models, the Wagon R isn’t modern by any stretch of the word.


When I look at my fuel consumption figures they are about 3-4 mpg lower than average so about 10% higher than expected. In reality as the engine is never running at full pelt it will be producing less output, let's say its average is 20kw to allow for hills and acceleration full loads carried etc, now I'm using 10% more fuel so a really rough calc means I'm using an extra 2kw somewhere, so using my aircon most of the time is perhaps the culprit.
There is no way on Gods earth an aircon system only uses 200 watts, why do you think the ECU compensates so much when it engages?
Im in total agreement with JRK.

Ok so an airconditioning system uses most power when it is under the highest load, when a car has an interior temperature if say 40’c, the outside temp is 30’C and the desired inside temperature is 20’C, then the system does this by compressing and expanding gas, the more heat the gas takes out of the car the more it wants to expand as it is carrying more energy and therefore the more power is needed to compress it it again, that extra energy is wasted as it’s radiated off by the condenser. As the temperature of the interior of the car reaches the desired temp, and you switch it to recycle the air, the target of 20’C is still the same but the amount of effort the air condiontion is having to put in would be minimal, reducing the ambient air temp from 21’C to 20’C the gas does not expand as much the demand on the aircon system is much lighter and therefore hardly any energy is needed to keep it ticking over.
So reducing the air temperature by 1’C obviously uses considerably less energy than dropping the temperature by 20’C over the same time period.

Stir a big pot of water with a spoon you’ll need energy to get the water moving, stop stirring and the water will then push the spoon round, same thing happens in aircon if the demand is low then next to no energy is needed to compress the gas.


The lower the output of the engine or driving economically then the difference will be greater. Before I got the aircon regassed on my 177bhp Rover 75 my average fuel consumption was 20mpg after it was sorted and the following year it dropped to 19 mpg. The lower power engine will quite clearly be working harder.

Which is it 3-4mpg or 1mpg :confused:
1mpg over the course of a week doing the same trips is not really of any concern using the aircon over the course of a year versus not using it and only getting a 1mpg change in economy isn’t even worth mentioning. The rover 75 (I assume it’s the v6 you) was a horribly dated and inefficient engine by modern standards and had an old style aircon system, and a relatively large cabin. So A ~5% increase over the course of year, not taking any other factor into to account such as wear and tear on the engine, tyres, tyre pressures, wind speed, air pressure and temperature, the amount the aircon contributed to the change may be considerably less than 5% (or more I concede) it’s not exactly however, a yard stick by which you can measure all cars. Especially not ones made 15 years later. These days the system is matched to the engine it’s used with, in the past they would put essentially the same aircon compressor into every car, with only differences made for mounting.


I'm confused - am I the only one. What I know is that my previous 100HP had climate control on permanently, except when I turned it off to see if the mpg changed. It didn't by a noticeable amount. Likewise the aircon in my current 4x4 TA - no significant difference.
The key word you mention is “significant” you can drive the same route to work every day for a month at the same time at the same temperature and still see a difference of 1-2mpg because of wind speed, things like rain or air pressure lots of things can make little difference to economy. Modern air conditioning does not make a “significant” difference. I notice no significant effect on fuel economy with any of my cars while using air con.

A modern ECU can compensate for the additional load by injecting more fuel when the compressor kicks in; this takes away the noticeable power loss you could feel with first generation systems (unless you're already demanding full power from the engine). You don't notice the additional power drain so much, (because the engine automatically compensates), but it's still there, and the impact on fuel economy is much the same.

The additional fuel still has to be accounted for; intelligent sensing can maximise the power when you most need it, but the total energy needed (which directly equates to fuel use) has to be made up later. For example, you can reduce the instant consumption by temporarily disengaging the alternator, but it'll have to work harder when you reengage it to recharge the battery, and that will burn the fuel you saved in the first place.

What will save fuel are systems which make use of energy which would otherwise be wasted; regenerative braking being one obvious example.

Modern systems can turn off and on the alternator as and when it will gather power most efficiently, for example when coasting in gear using no fuel at all the alternator can gather free power, but then switch off for the next up hill stretch. Old cars the alternator would be running near constantly trying to put charge into a full battery and generating heat that would be waste.
My VW has regenerative braking and so when driving normall there is little power going to charging the battery but when breaking the power is shunted into the battery to charge it rapidly to minimise power loss, not something fiat are doing but things like a freewheeling alternator do a basic version of this.
The car can be run leaner or richer by the ecu with no decernable increase or decrease in power but can have a significant affect on the fuel economy. Timing can be adjusted to change the power characteristics needed for when the aircon is on versus off. It’s a bit more complex than just increasing fueling to meet demand.

Newer aircon systems are more and more being run electronically, this means they can run at a constant speed without switching in and out, the motor can vary the speed of the pump to meet the environmental conditions. They also have variable compressors which can compress more or less at the same engine speed so that switching in and out is not needed again saving fuel and matching the air conditioning perfectly to the conditions to allow maximum economy, again this can be match so that when getting a move on the aircon is demanded less and when rolling in gear more power can be sent to the pump to gather a little, what would be otherwise lost energy. Also the engine can switch a mechanical aircon compressor in and out to match the torque characteristics of the engine, making use of wasted torque, or switching out when you are accelerating and need the extra boost, in the past the aircon would only switch on and off with wide open throttle, but you can still accelerate hard without fully pressing the pedal into the carpet, and while you do this the aircon saps power and makes the car less efficient, take you foot off the throttle and the aircon comes in and makes use of overrun energy. Also new compressor designs with better tolerances all reduce the amount of fuel and drag on the engine, needed to power them.
 
For the original question:

1. Does having aircon on use more fuel - yes, though vastly dependent on temperature/usage*

2. Ballpark? If you do 12000 miles a year it probably costs £160 a year max though probably less**




* So does morbid obesity, windows open, roof bars, fat/flat tyres, driving with a topped-up tank, thrashing it........etc

**40mpg versus 44mpg at £1.30 a litre
 
Which is it 3-4mpg or 1mpg :confused:
1mpg over the course of a week doing the same trips is not really of any concern using the aircon over the course of a year versus not using it and only getting a 1mpg change in economy isn’t even worth mentioning. The rover 75 (I assume it’s the v6 you) was a horribly dated and inefficient engine by modern standards and had an old style aircon system, and a relatively large cabin. So A ~5% increase over the course of year, not taking any other factor into to account such as wear and tear on the engine, tyres, tyre pressures, wind speed, air pressure and temperature, the amount the aircon contributed to the change may be considerably less than 5% (or more I concede) it’s not exactly however, a yard stick by which you can measure all cars. Especially not ones made 15 years later. These days the system is matched to the engine it’s used with, in the past they would put essentially the same aircon compressor into every car, with only differences made for mounting.


Hi.
I'd suggest you do some research on the 75.

The K4 & KV6 were highly developed and efficient engines at the time, granted not as efficient as today's units. I don't see where engine efficiency really matters in this discussion for a given output the load will have a bearing, a low output engine will use more of its "available power" to run ancillaries than a bigger engine that can produce more "available power".

So having Air Con in a car with a small engine will make more of a dent in performance and fuel use than a larger car.

With respect to the 75 system it had full climate control with a system that can cool one side and the other side at a different temperature, all done with temperature sensors and controlled by a separate ECU. At the time the car was reckoned to be one of the most sophisticated electronically and the very same systems were used in BMW cars up to the end of the naughties.

So perhaps you can see that why I only lost 1 mpg in the 75 and up to 4 mpg in the Panda, all recorded in Fuelly.

Even though the Panda is smaller it actually has a slightly larger glass area than the 75 and it has a longer cabin area so I'm not sure if your calculations really stand up.
 
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Hi.
I'd suggest you do some research on the 75.

I spent far too much time under the bonnet of Rover 75s in the early 2000s working as an electrical engineer in the automotive trade thanks and know all about it’s “sophisticated” electronics system.... (y)

Designed by Germans, nailed together by brummies :rolleyes:
 
Hi.
A bit unfair to say the Brummies nailed the car together. There are more 75 survivors than Jaguars and Mondeos of their time. The slated K4 had a hard life in the 75 due to a silly header tank, leaks from pipework and failing cooling fans especially the three speed and two speed with an underrated series resistor. Yes they are nearly 20 years old now but since 2012 to 2017 before bad health I did plenty of trouble free miles in a car that was unfairly slated, I had two a 1.8 1999 and a 2.5 V6 2000.
 
All straying a bit from the original question here?

Does air con in the Panda work well?
Yes.
And does air con have effect on fuel consumption?
Yes - we all seem to agree that it does, to varying degrees.

But I'd say the comfort benefits outweigh the small increase in journey cost.

Like all things that make the engine work harder: under-pressure tyres, using the lights at night or the wipers in the day, carrying unnecessary weight in the boot... all these things have a small but measurable effect. But its the value, not the cost, that needs considering.

If you work out the fuel cost for a 100 mile trip, you see that its not too expensive to drop the mpg a bit: 100 miles at 50mpg and fuel at £1.30 a litre costs about £11.70 for fuel. Same trip at 48mpg costs £12.35. So, 65p over 100 miles to stay comfortable I'd say is worth it.


Edit: sorry, I spot @AB100 posted similar reply yesterday, 'lost in the debate'. Should we leave this one as 'answered' now...
 
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Yes I agree, perhaps the thread has run its course and I'm sorry I digressed, although the 75 I'm sure and its bigger bulk and engine was good evidence that performance and fuel use is less noticeable than in the Panda.
Who cares really if you use a few millilitres of extra fuel if you are more comfortable and alert being cool. Mine is solidly on and it is great, cool and comfortable.
 
Really appreciate the response to this and the info about the Panda’s air con.

The drive back on Friday left my back sweating like crazy! Thankfully the sun is less brutal in the mornings than the afternoons.

Can’t wait to get my next Panda when the time comes. It’ll be an Easy or above model now though with the need for air conditioning now a must
 
We've had this discussion before.

Unfortunately, that's just not true.

I'd agree modern A/C systems are much improved from those of twenty years ago, but in the final analysis, there's no way round the basic physics.

Just calculate the power needed to cool the car by 15C, calculate the power needed to propel the car at a steady 50mph, and compare the two. No amount of fancy electronics can change the fact that the additional power needed to cool the car has to be paid for in fuel.

As usual a good point well put. Using the eco meter you can see the effect of consumption too. Its certainly 5mpg. The cooler on the panda is vast for the size of car and it does a good job of cooling as one would expect from a southern european. Buy a white car the difference in internal temperatures compared tom a dark one is 40-50C on a hot sunny day. You can hide in snow drifts too.
 
Buy a white car the difference in internal temperatures compared tom a dark one is 40-50C on a hot sunny day. You can hide in snow drifts too.


When researching for this thread, I came across a study done in California that looked at the impact of car colour on fuel usage (dark cars need more A/C power to maintain the same cabin temperature on sunny days) - I'll see if I can find it again.


Edit: Here it is. Read this as well.
 
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I can vouch for the A/C effectiveness living in southern Spain. The blast from the eye level vents is welcoming. I usually only use the A/C on the dust track, once on the road, open the windows. Fuel consumption dropped a bit from 48 to 46.5 so no issues there.
As for the colour.......I work in a white t-shirt anywhere. Put a dark blue one on and feel the temperature change to your body (winter only)! Same thing to the car.....my wife selected Mediterranean metallic blue.....didnt want silver!!
 
When researching for this thread, I came across a study done in California that looked at the impact of car colour on fuel usage (dark cars need more A/C power to maintain the same cabin temperature on sunny days) - I'll see if I can find it again.


Edit: Here it is. Read this as well.

In 1976 I had a maroon car. Inside there was a thermometer that ran up to 240F. On the first day I left the car the thermometer which was a metal coil, it unwound and tore the needle out of its mounting. After painting the roof white with a new thermometer installed the temp hung at around 140F! I am thinking of doing the Panda roof white using a wrap, and the Bravo roof in Chrome just to be different. CHrome however has been quoted at £110 per m2. If I take the plunge I will do a few tests. Its clear to me that its a lot more that 5 or 6 degrees though so I wonder why the conservative figures in the report.
 
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