RE: Turn the Air Con on
Tuesday 27th July 2004
Turn the Air Con on
...or you might get the lurghee
Motorists must switch on their air-conditioning units once a week, 52 weeks of the year to help avoid the build up of unpleasant odours. That’s the advice of car care people, Comma, after its research discovered that more than a third of all motorists admit to never using their air con out of the summer months.
Much of the blasé opinion could be explained by the finding that 2 in 5 don’t consider air con to be an essential feature for their vehicle.
While air conditioning can provide cool comfort during the warmer months, if it isn’t used throughout the year it can quickly become a breeding ground for Sick Car Syndrome triggering fungal spores like Cladosporium and Aspergillus.
Comma research revealed the worst offenders for not looking after their air con system are motorists over 55, with 50% readily admitting to limited summer month use. In comparison, drivers of cars under a year old are the most likely to continually use air con, with 72% keen to keep their new car in tip-top condition.
"Most people associate air con with summer, but it is equally important to use during the colder months as well," commented Comma spokesperson Mike Bewsey. "Once established, the bacterial spores quickly multiply to deliver a rather nasty, lingering smell in the car, something buyers of used cars will instantly recognise."
Not surprisingly Comm flog an air con cleaner product. See visit www.commaoil.com
Discussion
aww999 said:
I got mine regassed at the weekend after three years (!) of non-use. Working great now, but I have picked up a sore throat/headache. Coincidence?
Yep, there is a bug going around at the moment, I'm just getting over it. Starts of with Sore throat/Headache, turns into cold with sweats etc.
Graham said:
I dont think i've ever turned the climate control on the disco off, up or down but never off...
maybe thats one reason the mpg is so sh1tbut then again maybe there are other reasons for that
g
I agree. I also find as soon as the aircon goes the fuel of have in the tank magically goes away. I wonder if you use the a/c all the time the ECU will adjust to suit the car better? Anyone know the answer to that?
Also I too heard that the lube is inside and if you dont use the a/c it dries the seals out or something like that. ESSO must be in on some sort of deal here with the a/c company.
You tell it will cause damage we get them buying more fuel haypresto everyone happy NOT
Bobbins said:
I get a sore throat if it's left on all the time. I read that (ideally) you should turn it off a few mins before end of journey to allow it to dry out, otherwise if the system is left wet then it breeds nasty things.
Trouble is, I always forget to turn it off.
warning
alert!!! Actually the best technique is keep it turned on 100% as above advice. That is what people in the aircon business do.
It doesn't affect fuel consumption so much as most cars these days have variable output compressors. They are set to keep the evaporator at 1-2 degrees C to prevent condensation freezing and blocking airflow. The air is brought back to your set temperature by using the heater. The system maintains this temperature in the evaporator by monitoring the pressure of the refrigerant. Thus the output of the compressor varies acording to how much work is needed.
On a cool day not much is needed, on a hot humid day quite a lot of power, about 12kw say ~8bhp, if on recirculation mode less power as the incoming air is cooler and less humid.
Think of it like an alternator, nobody turns the alternator off because its a nice sunny day and you don't need much lighting on.
Finally the stink. One way to avoid this without need for additives is every month/ maybe every two weeks, turn on your aircon full welly, ie max cold for ten minutes. Then turn on your air con off and heater full welly for ten minutes to dry all the pipes out. Sorted.
Hope that helps.
FiF
/
mode off Flat in Fifth said:
I get a sore throat if it's left on all the time. I read that (ideally) you should turn it off a few mins before end of journey to allow it to dry out, otherwise if the system is left wet then it breeds nasty things.
Trouble is, I always forget to turn it off.
warning
Actually the best technique is keep it turned on 100% as above advice. That is what people in the aircon business do.
It doesn't affect fuel consumption so much as most cars these days have variable output compressors. They are set to keep the evaporator at 1-2 degrees C to prevent condensation freezing and blocking airflow. The air is brought back to your set temperature by using the heater. The system maintains this temperature in the evaporator by monitoring the pressure of the refrigerant. Thus the output of the compressor varies acording to how much work is needed.
On a cool day not much is needed, on a hot humid day quite a lot of power, about 12kw say ~8bhp, if on recirculation mode less power as the incoming air is cooler and less humid.
Think of it like an alternator, nobody turns the alternator off because its a nice sunny day and you don't need much lighting on.
Finally the stink. One way to avoid this without need for additives is every month/ maybe every two weeks, turn on your aircon full welly, ie max cold for ten minutes. Then turn on your air con off and heater full welly for ten minutes to dry all the pipes out. Sorted.
Hope that helps.
FiF
/
Thank, thats very helpfull, will put that advice into action.
I've always run my a/c first of the month, also I op the four wheel drive, both for lube purposes.
On many cars the a/c will op on defrost. (though you will not realise)
I don't think the mpg is affected as much as many think, the car has much less drag with the windows up so this will compensate for some of the compressor load.
I'm not sure running the heater will dry out everything after running the a/c because of the blend gate. Just make sure you see a water puddle under the car after running the a/c that should keep you healthy.
Jeff
On many cars the a/c will op on defrost. (though you will not realise)
I don't think the mpg is affected as much as many think, the car has much less drag with the windows up so this will compensate for some of the compressor load.
I'm not sure running the heater will dry out everything after running the a/c because of the blend gate. Just make sure you see a water puddle under the car after running the a/c that should keep you healthy.
Jeff
markpetrie said:
I'm sorry guys but I have to disagree. I tested my aircon for the last week and the consumption of fuel has increased. Today especially I was making sure I took it easy with the old throttle and still the fuel reduces more than when I don't have the aircon on.
Any ideas?
MarkP, I think you are perhaps misinterpreting the comments.
Nobody, at least almost nobody, is saying that turning the aircon on does not increase fuel consumption, it does. The answer to how much is like the answer to how long is a piece of string.
Turn on electrical equipment and you increase the consumption. Lights? Wipers? Heated rear screen? They all draw power from the battery so the alternator has to work harder to replace that power. Thus the alternator consumes more of the power output and thus more fuel is burnt, can't get owt for nowt.
When you turn off the equipment the alternator reduces its power output, thus less power is consumed, ditto fuel, back to as you were.
The thing is that the effects are so small that hardly anyone notices the consequences and no-one, with the exception of die-hard fuel economy freaks, do anything about it.
As I said above think of the aircon compressor like the alternator, it just does enough to keep the set temperature, but in doing so it has to take power from the engine and so fuel consumption WILL go up. When the temperature is OK it stops taking power from the engine, but it does it all automatically, either by the variable output compressor or in some systems by a clutch arrangement.
How much extra fuel is where the string length comes in. Ambient air temperature, humidity, recycle mode on/off, state of maintenance of the aircon are allsome some of the issues.
So if you do your back to back test in weather like recent times you will get a significant increase.
What is the alternative? Driving with open windows? That is also proven to increase fuel consumption.
Another factor is the size and power of the vehicle. Remember from the earlier post the typical output of an aircon at full welly in UK is 12kw (~8hp) and putting that in perspective a typical home freezer is ~1.2 kw iirc.
I am sure you can appreciate that the aircon in hot humid weather like recently wil hit the performance and fuel consumption of a small low powered car quite markedly. Yet for a large powerful vehicle the effect might be relatively insignificant, rather in the same way that putting the lights on is an insignificant effect.
Every year the SOE (IRTC) organise a fuel consumption day for fleet operators where various things are tried under controlled conditions. Its aimed at heavy goods and bus operators but light vehicles are included.
The other year there was an attempt to follow up earlier findings that on cars the effect of air con on fuel consumption was less than having the windows open. One test proved conclusively it also applied to heavy artics, another test was less conclusive due to other test related factors. The conclusion was iirc that on balance it was better to use aircon, remember these tests were on heavy vehicles with 400bhp or so.
Finally think of it another way. If you don't use the aircon regularly as advised right at the beginning of the thread, you WILL land yourself in for a large bill at some point to keep it in working order. Which is better the cost of the extra fuel or the repair bill?
Up to you to decide.
Sorry for the long post. Hope it helps.
FiF
briano said:
Living in Cyprus, I run a/c all the time, today is 32C with 70 % humidity. Mark, I wonder if it is the current higher temperatures which are causing your increased fuel consumption; my fuel consumption increases from about 25mpg in the Winter to 22mpg in the Summer.
Same temperature today as in the UK (well my car said 31 deg anyway, so close). Defintely an aircon on day.
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