ahmett
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i swear those leds make things much worse = )
Technical Automatic Climate Control
- Thread starter Mick F
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Technical Automatic Climate Control
Many years ago I actually had a client whose name was Richard Head.
Personally I'd have changed my name by Deed Poll.
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So if you have a 80" TV you should run it all the time?
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The first part doesn't apply to new cars, certainly not any with CANBUS A/C control. The A/C is always off when you start the car, the ECU will only turn it on once the engine is running smoothly. Personally even with older cars that had the A/C on 100% during summer, I've never had this issue.
Part B doesn't shouldn't really apply to the 500, the ECU is programed to produce extra torque when the A/C is on, and disengages completely at high load. This is why most people will swear A/C makes no difference, Fiat programmed it that way. With older small cars you can absolutely tell if the A/C is on, sometimes to the point where I'd rather sweat it out than loose so much power.
Could there be something wrong with your car?
cockerhoop
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now using auto setting with temp 24
all warm and toasty all the time
all warm and toasty all the time
Sweetsixteen
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Never buy a car with cylinder deactivation/ displacement on demand then
With an LED TV, if you reduce the picture size the black portion of the screen is 'off' and does indeed save power
So it's OK to use you TV only when you want to watch it, but 'deliberately' turning the A/C off when it's not needed is not?
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Sweetsixteen
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But they didn't have 'through flow' ventilation, so they worked much better if you - wait for it - opened a window also!
Never buy a car with cylinder deactivation/ displacement on demand then
With an LED TV, if you reduce the picture size the black portion of the screen is 'off' and does indeed save power
So it's OK to use you TV only when you want to watch it, but 'deliberately' turning the A/C off when it's not needed is not?
The ACC is always used in my car except when the roof is down as then it's doing nothing of benefit to me.
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Was once common. I guess Landrovers were the last ones with forward opening vents. My Jeep lets me fold the windscreen flat- cooling airflow and a smaller frontal area
Wow......
Lots of people here don't really understand aircon, don't get me wrong lots of people have a good idea but there is a lot of miss information in this thread.
MEP kept trying to make a very valid point, just because the ac light is on doesn't mean the compressor is active.
So on starting as pointed out the compressor clutch is disengaged until the canbus system is happy the engine is running, sometimes you'll hear the compressor click in a second or so after starting. So it should never stall a car especially a 1.3mjd
Once running the system will cycle, so the compressor will get the pressure up in the system and once there it can take a while for the high and low pressure sides of the system to equalise, during this time you will still get nice cool air but the compressor will be switched off, you'll notice this more on cars low in gas as the air will get cold and warm with the cycles.
Wide open throttle the ecu will cut the ac (usually anything above 80% throttle) this prevents the aircon sapping power when you need it.
Efficiency issues, a fully gasses system is most efficient as it won't take the compressor long to get up to pressure and it takes the longest time for equalisation, remember during this period the compressor is off. A system low on gas my need the compressor running constantly which will have a major effect on fuel economy.
The difference in hot and cold weather. It's a long explanation so bare with me...
In hot weather the compressor pushes the expanded gas, adding energy, into the condenser to be cooled down to remove heat energy, before passing to the expansion valve, when the gas expands loosing more energy and thus loses heat getting very cold and passing through the evaporator where it takes the energy out of the surrounding air, making the air cold and the gas warm again. The gas then goes through the receiver/dryer to remove any contaminants or moisture in the gas and then back round to the compressor to begin the cycle again.
On a hot day the gas is already carrying a lot of energy, the compressor has to work hard to compress the already expanded gas, the condenser then has to work harder to remove more heat, when expanded in to the evaporator the gas is faced with hotter air and so more energy to exchange, meaning the gas is heated more and expands more, before passing to the dryer and back to the compressor
On a cold day. The compressor compresses the gas and it still gets hot, however the condenser is much colder and cools the gas much easier, it then expands greater when passing into the evaporator (much greater pressure differential) and so the gas more easily exchanges heat with the air in the cabin. The gas doesn't take so much heat out of the air because the air is already colder and so the gas does not expand as much on its way out of the evaporator. The denser gas passes round to the compressor which finds it much easier to compress the denser gas.
The upshot of this is that on a cold day the aircon draws a lot less power from the engine than in the height of summer, even I the compressor is running for the same period of time. No different to an alternator charging an empty battery will use more engine power than an alternator attached to a fully charged battery.
Cooling already cold air is easier than cooling hot air.
So in the winter running your aircon will use very very little extra fuel. But the cold evaporator will cause any moisture in the air to condense on its surface which drips into the drain and out through the bulk head on to the road. This takes the moister out of the air that would other wise be steaming up the windows. Hence why aircon clears the windscreen much faster then non aircon. On the flip side on a hot day the aircon will be more demanding an use more fuel.
Someone mentioned air con servicing. And replacing the dryer, just to make a point the 'dryer' has nothing to do with drying the air, it's just following replacement of these parts the system was working better and a nice cold efficient system freezes the bugs and stops the damp musty smells by efficiently removing the water by condensing it on the evaporator (confusing I know) A poorly working system cycles cold condensing the water then warm giving the bacteria a nice wet warm safe haven. A clean pollen filter is good but doesn't need changing every year, (every 3 is fine) check the drain is clear and not blocked and being well gassed is sufficient,
The best test of any air con system is on a hot day (+20degreesC) to check ambient temperature, then measure temp at the vents, anything over a 15degreeC drop is perfect. No need to do anything else.
Properly cycling the system summer and winter will prevent the bacteria and smells saving wasting money on air con cleaning chemicals. In winter the system is designed not cool below about 5degreesC to prevent the moisture freezing. Another reason it won't use so much extra fuel, compared to summer)
This leads me on to the automatic climate control,
These systems when set to auto, are supposed to wait for warm coolant to be available before blasting the fans. The aircon light being on simply means the acc is managing the switching of the compressor, it will turn it on and off as needed but will operate all the time to aid with demisting in cold weather and cooling in hot weather, but this is obviously managed with regard to the temperature you set on the dash so will be more efficient then simply running the aircon all the time in manual mode as once the desired temp is reached it will cycle off the aircon and slow the cabin fans. If you are warming the car against cold external air, the aircon isn't hardly much energy anyway.
The fiat ACC system is however crap and is very slow to respond to changes in temperature. Which is why people get frustrated with it. So you set it to 20, the car heats the air to 20 but takes 3-4 mins to realise this and when it does the temp is 22 and so it then starts cooling down to 18 then back up to 21 then down to 19 blasting the fan speed up and down and generally being annoying, before eventually settling at the desired temp by which point you've already gotten fed up and switched it off auto to control the fan speed yourself.
I probably could ramble on some more but I will leave it there, basically aircon systems are simple in the way the work, but complex in the science, they are self managing in regards to energy use, which is dictated by ambient temperature, at either end of the system, they don't run dumb and just consume power all the time.
Lots of people here don't really understand aircon, don't get me wrong lots of people have a good idea but there is a lot of miss information in this thread.
MEP kept trying to make a very valid point, just because the ac light is on doesn't mean the compressor is active.
So on starting as pointed out the compressor clutch is disengaged until the canbus system is happy the engine is running, sometimes you'll hear the compressor click in a second or so after starting. So it should never stall a car especially a 1.3mjd
Once running the system will cycle, so the compressor will get the pressure up in the system and once there it can take a while for the high and low pressure sides of the system to equalise, during this time you will still get nice cool air but the compressor will be switched off, you'll notice this more on cars low in gas as the air will get cold and warm with the cycles.
Wide open throttle the ecu will cut the ac (usually anything above 80% throttle) this prevents the aircon sapping power when you need it.
Efficiency issues, a fully gasses system is most efficient as it won't take the compressor long to get up to pressure and it takes the longest time for equalisation, remember during this period the compressor is off. A system low on gas my need the compressor running constantly which will have a major effect on fuel economy.
The difference in hot and cold weather. It's a long explanation so bare with me...
In hot weather the compressor pushes the expanded gas, adding energy, into the condenser to be cooled down to remove heat energy, before passing to the expansion valve, when the gas expands loosing more energy and thus loses heat getting very cold and passing through the evaporator where it takes the energy out of the surrounding air, making the air cold and the gas warm again. The gas then goes through the receiver/dryer to remove any contaminants or moisture in the gas and then back round to the compressor to begin the cycle again.
On a hot day the gas is already carrying a lot of energy, the compressor has to work hard to compress the already expanded gas, the condenser then has to work harder to remove more heat, when expanded in to the evaporator the gas is faced with hotter air and so more energy to exchange, meaning the gas is heated more and expands more, before passing to the dryer and back to the compressor
On a cold day. The compressor compresses the gas and it still gets hot, however the condenser is much colder and cools the gas much easier, it then expands greater when passing into the evaporator (much greater pressure differential) and so the gas more easily exchanges heat with the air in the cabin. The gas doesn't take so much heat out of the air because the air is already colder and so the gas does not expand as much on its way out of the evaporator. The denser gas passes round to the compressor which finds it much easier to compress the denser gas.
The upshot of this is that on a cold day the aircon draws a lot less power from the engine than in the height of summer, even I the compressor is running for the same period of time. No different to an alternator charging an empty battery will use more engine power than an alternator attached to a fully charged battery.
Cooling already cold air is easier than cooling hot air.
So in the winter running your aircon will use very very little extra fuel. But the cold evaporator will cause any moisture in the air to condense on its surface which drips into the drain and out through the bulk head on to the road. This takes the moister out of the air that would other wise be steaming up the windows. Hence why aircon clears the windscreen much faster then non aircon. On the flip side on a hot day the aircon will be more demanding an use more fuel.
Someone mentioned air con servicing. And replacing the dryer, just to make a point the 'dryer' has nothing to do with drying the air, it's just following replacement of these parts the system was working better and a nice cold efficient system freezes the bugs and stops the damp musty smells by efficiently removing the water by condensing it on the evaporator (confusing I know) A poorly working system cycles cold condensing the water then warm giving the bacteria a nice wet warm safe haven. A clean pollen filter is good but doesn't need changing every year, (every 3 is fine) check the drain is clear and not blocked and being well gassed is sufficient,
The best test of any air con system is on a hot day (+20degreesC) to check ambient temperature, then measure temp at the vents, anything over a 15degreeC drop is perfect. No need to do anything else.
Properly cycling the system summer and winter will prevent the bacteria and smells saving wasting money on air con cleaning chemicals. In winter the system is designed not cool below about 5degreesC to prevent the moisture freezing. Another reason it won't use so much extra fuel, compared to summer)
This leads me on to the automatic climate control,
These systems when set to auto, are supposed to wait for warm coolant to be available before blasting the fans. The aircon light being on simply means the acc is managing the switching of the compressor, it will turn it on and off as needed but will operate all the time to aid with demisting in cold weather and cooling in hot weather, but this is obviously managed with regard to the temperature you set on the dash so will be more efficient then simply running the aircon all the time in manual mode as once the desired temp is reached it will cycle off the aircon and slow the cabin fans. If you are warming the car against cold external air, the aircon isn't hardly much energy anyway.
The fiat ACC system is however crap and is very slow to respond to changes in temperature. Which is why people get frustrated with it. So you set it to 20, the car heats the air to 20 but takes 3-4 mins to realise this and when it does the temp is 22 and so it then starts cooling down to 18 then back up to 21 then down to 19 blasting the fan speed up and down and generally being annoying, before eventually settling at the desired temp by which point you've already gotten fed up and switched it off auto to control the fan speed yourself.
I probably could ramble on some more but I will leave it there, basically aircon systems are simple in the way the work, but complex in the science, they are self managing in regards to energy use, which is dictated by ambient temperature, at either end of the system, they don't run dumb and just consume power all the time.
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Sweetsixteen
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Lot of reasoning there!
Of course, some of it presupposes that the car has an ecu programmed to control, and over-ride where necessary, the function of the aircon compressor.
There must be many owners, myself included, who have older vehicles without an ecu mastermind.
Of course, some of it presupposes that the car has an ecu programmed to control, and over-ride where necessary, the function of the aircon compressor.
There must be many owners, myself included, who have older vehicles without an ecu mastermind.
If your car was built in 1989 and has carbs or a very early rudimentary fuel injection system, but this is the standard operation of aircon for the last 20 years
OP
OP
Thanks Andy,
You've explained in technical terms what I was trying to get across up-thread.
The only real experience I've had with aircon is in our 2001 1.6L 16v Clio. It has a manual system and it's been switched on and running for all of its 95,000miles.
It works well, it doesn't impact on the fuel consumption to any degree, and we're dry, clean, fresh, cool/heated ............. and happy.
Long may aircon continue.
ACC is even better.
Thanks,
Mick.
You've explained in technical terms what I was trying to get across up-thread.
The only real experience I've had with aircon is in our 2001 1.6L 16v Clio. It has a manual system and it's been switched on and running for all of its 95,000miles.
It works well, it doesn't impact on the fuel consumption to any degree, and we're dry, clean, fresh, cool/heated ............. and happy.
Long may aircon continue.
ACC is even better.
Thanks,
Mick.
Andy
You seem to know the functions of ACC, maybe you can answer a Q I have?
I haven’t found a way to circumvent the function in the Automatic climate controls CCU that if I put it in manual and set desired temp, vent and put the fan on ex. 4 bars and then turn the ignition off then back on again the CCU remembers al settings except the fan settings. It doesn’t mater if the engine is hot or cold. I’ve tried it on 2 different cars built 2013 and the function is the same. I´ve also tried to talk with two different Fiat service tech´s and they look at me as if I´m from the moon asking questions like that‼ The problem I have is that I need the fan to start when I pull ignition on the CCU this is due to I have a Webasto heater installed and I would like it to defrost the ice on the windows without having to manually start the fan. Any input from anyone how to solve this problem is appreciated.
Regards Rob
You seem to know the functions of ACC, maybe you can answer a Q I have?
I haven’t found a way to circumvent the function in the Automatic climate controls CCU that if I put it in manual and set desired temp, vent and put the fan on ex. 4 bars and then turn the ignition off then back on again the CCU remembers al settings except the fan settings. It doesn’t mater if the engine is hot or cold. I’ve tried it on 2 different cars built 2013 and the function is the same. I´ve also tried to talk with two different Fiat service tech´s and they look at me as if I´m from the moon asking questions like that‼ The problem I have is that I need the fan to start when I pull ignition on the CCU this is due to I have a Webasto heater installed and I would like it to defrost the ice on the windows without having to manually start the fan. Any input from anyone how to solve this problem is appreciated.
Regards Rob
I'm going to assume while the heater is in use the engine is off?
The climate control is designed to run the fan low till the car has warmed up, this is to prevent the car blowing cold air in your face, in the cold weather. Unlike most cars without climate control there is no basic resistor pack or fan switch it's all controlled electronically and digitally. The resistor is replaced with pulse width modulator which pulses the power to the fan to control the speed, and you can't tap into this with an analogue system.
with a webasto heater, I would look into fitting a separate control for the fan, so that when the heater is on the fan is powered completely separately from the climate control system.
The other issue is running the battery down so you may not want the fan to start running till the coolant is warmed up. I believe webasto have control units that can manage this but they are a bit costly
