# Car A/C - How do you use yours?



## richtung (Apr 14, 2008)

Hi Folks,

My car is a MK5 Golf GTI ED30.

Noticed the white fungi/mold stuff growing growing in the insides of the rear windows again. No obvious leaks etc. I figure the dry air from the aircon isn't reaching the back of the car.
I usually have the blower (with A/C on all the time) on the demister setting -ie blowing onto the windscreen. Once the screen is demisted i just turn down the blower to a couple of bars.
It dawned on me the other day that this might not provide optimal air circulation. 

Im now getting into the habit of setting the blower to the screen/to the face/footwell once the windscreen has been demisted in the hope of getting the air circulating a bit better.

Im interested to hear how other use their blowers / air con?

Thanks

Rich


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## Kerr (Mar 27, 2012)

I have mine on most of the time. I hear too many stories of issues when it's idle too long. 

Maybe it's because I've got a bigger engine, but I don't notice any drop off in fuel economy when using it.


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## Pittsy (Jun 14, 2014)

Climate on all the time, vents on auto unless the windscreen is iced up then just adjust the temp up and down accordingly:thumb:


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## Sharpy296 (Jan 18, 2017)

Pittsy said:


> Climate on all the time, vents on auto unless the windscreen is iced up then just adjust the temp up and down accordingly:thumb:


This... Climate control on all the time. It will decide when / if the A/C needs to be on and you can see the compressor kicking in on mine if you open the bonnet.

Leaving the aircon turned off means that the that seals in the system dry out and crack, then you come to use it and have no gas in the system. The gas often has a lubricant specifically for keeping the seals in good order.

I dont notice a difference in economy, I think new cars have alrgely resovled this issues, but I also have a big engine, that said I dont notice it in the wifes SEAT either.


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## bigup (Jun 4, 2009)

Aircon/Climate on at 21C/22c all the time is what is recommended

i admit i don't do this though, have old school of thought - burns petrol


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## Cookies (Dec 10, 2008)

Mine is always on, generally always to the screen and the footwells. As bigup has said, I have mine set at 22 degrees. It seems to be a fairly comfortable temperature most of the time.

Cooks

Sent from my D6603


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## millns84 (Jul 5, 2009)

Only ever use mine when the car's steamed up and blowers won't clear it or when it's too hot to rely the sunroof. Never had any issues with it and my current car's 14 years old.

I used to notice lower power in previous small engined cars and it's the same with our family car, but in the Jag I don't notice it (4.2 V8 with 400bhp though...).


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## GleemSpray (Jan 26, 2014)

I don't use it as a natural habit, as i am old enough to have driven quite a large part of my life in cars that didn't have much in the way of usefull a/c ... 

But I do leave it on low when i remember, in my current MK 6 Golf, as continual use seems to reduces the terrible winter windscreen fogging that these Golfs are notorious for.


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## Brian1612 (Apr 5, 2015)

Usually on all the time at low, just adjust the temp accordingly. Apparently using it frequently keeps it from needed re-gassed longer.


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## Starbuck88 (Nov 12, 2013)

Always have A/C button on.


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## leehob (Jul 9, 2014)

Always on regardless of whether temp is on warm or cold :thumb:


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## robertdon777 (Nov 3, 2005)

GleemSpray said:


> I don't use it as a natural habit, as i am old enough to have driven quite a large part of my life in cars that didn't have much in the way of usefull a/c ...
> 
> But I do leave it on low when i remember, in my current MK 6 Golf, as continual use seems to reduces the terrible winter windscreen fogging that these Golfs are notorious for.


The AC causes the Fogging on these.... I know it sounds the complete opossite to what should happen (and does on other systems)

But just ask on Forums like the Skoda one (same system)... Go against your instinct and leave the AC off.... Yes OFF.

What will happen is the car will mist up like usual, but keep at it and over the next couple of days...he presto no misting up.

The system holds excess water, when the car starts up the AC doesn't have time to get rid and the result is a very misty windscreen in the Morning which can take a good 5 -10mins to clear.

I know this from having the same system on my Octavia VRS for near 6 years... and only discovering the answer in the final 1.5years of ownership via the Skoda Forum. The car was an absolute pain in the morning trying to demist with the AC on, massive window fog.


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## graham1970 (Oct 7, 2012)

robertdon777 said:


> The AC causes the Fogging on these.... I know it sounds the complete opossite to what should happen (and does on other systems)
> 
> But just ask on Forums like the Skoda one (same system)... Go against your instinct and leave the AC off.... Yes OFF.
> 
> ...


Oh right.... Cheers bud,might explain why my partners citigos windscreen is misted to f*** in the morning.
She only does a few miles a day....skoda told her to leave the ac on!!?

Sent from my D5803 using Tapatalk


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## robertdon777 (Nov 3, 2005)

graham1970 said:


> Oh right.... Cheers bud,might explain why my partners citigos windscreen is misted to f*** in the morning.
> She only does a few miles a day....skoda told her to leave the ac on!!?
> 
> Sent from my D5803 using Tapatalk


Its the natural thing to do, leave it on but it makes it worse first thing on a Cold Morning on these systems.... Other makes can be fine though. Merc seem to be ok, Both our Mercs are fine but my Citroen also does it with AC on.

Just fight through the initial misting you will get once you turn it off, after maybe 2 days you should notice a massive difference..... Mine used to drive me mad, almost had to mop the screen of water before, after it was like a normal car.


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## graham1970 (Oct 7, 2012)

Will give it ago mate,thanks for the tip

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## PugIain (Jun 28, 2006)

Mine is on permanently.


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## Harry_p (Mar 18, 2015)

I leave my auto climate control on feet + screen and 21c, with fan speed on auto.

Turn on ac occasionally over winter to keep the seals lubricated, whenever it starts misting up, or whenever the outside temperature is close to or above my desired interior temperature.


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## donnyboy (Oct 27, 2005)

I thought that aircon/climate control didn't work below a certain outside temp? Something to do with the gas being too cold?


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## CoOkIeMoNsTeR (Mar 6, 2011)

Full auto climate set to 17 degrees most of the time, only occasionally change the settings


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## Bristle Hound (May 31, 2009)

My S4 has climate control which is left on permanently

My wife's MINI has 'normal' AC which is also on permanently


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## Turbo Tony (Mar 20, 2012)

My AC is always on in all my cars. In the Volvo, the switch is inverted, so it glows when it's turned off, which is a big hint that they want you to leave it on all the time.


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## sshooie (May 15, 2007)

Always leave mine on, helps with demisting and keeps the system lubed...


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## Crafty (Aug 4, 2007)

Set to auto and 20 degrees.

Regardless of what you are doing up front I wouldn't expect to see mold in a car anywhere. Something isn't quite right there, the only time I've seen mold is when a car has a leak. Are the spores on the window itself or in the rubber seals ?


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## neilb62 (Jul 30, 2007)

On 24/7 and adjust the temp as needed....


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## chrissymk3 (Jul 6, 2015)

On all the time at 20 degrees here with fans set to auto


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## Squadrone Rosso (Aug 11, 2009)

On all the time. Everything in auto with just a quick boost if things get steamy.


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## Liam-R32 (Feb 13, 2016)

Be mk4 golf seems always to have all the windows misted up, I only do shirt few minute journeys, so maybe the theory if the climatronic dumping excess water into the cabin could be right. Il try keeping it on econ for a few days.


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## rob267 (Nov 27, 2015)

Lol. Well i just found out that my cars air con is on all the time. Will be turning that off tomorrow. 

Dont like it on all the time. 
Only had the car a few weeks so excuse my stupidity 😀

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## baxlin (Oct 8, 2007)

On auto all the time, adjust temperature as and when, both in my Volvo (OK, turn it off if I remember when the top's down), and Mrs B's Skoda Fabia, no problems despite earlier comments about Skoda.

Re fuel usage, a heavy right foot and late braking will use a lot more, IMHO.


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## camerashy (Feb 9, 2014)

Interesting replies as I have always turned mine off and use it as required
I did read in a motor journal many years ago that you should use it at least once a month


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## Blueberry (Aug 10, 2007)

Mines on all the time - I have climate control. Not had any problems with mod growing or anything.


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## twk333 (May 20, 2017)

Manual-style, on all the time in my old car. Tons of mold for 10 of 12 years. 

Climate control, on all the time in my new car. No problems for over a year so far. 

Not sure if it's the car or the 500g pouches of dessicant at the rear window and in the trunk. 

Probably car as I now have rear window vents & cooled front seats.


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## moochin (Mar 17, 2009)

Mines on all the time, if I get wet before jumping in the car I'm back to being dry in no time at all. 

Sent from my SM-G935F using Tapatalk


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## Caledoniandream (Oct 9, 2009)

Climate control, year round, all the time.
Never drive with windows open, if you see the dirt on the outside of your car, you can imagine what comes in when you have the windows open.


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## SuperchargedLlama (Apr 25, 2008)

Blimey...I just turn mine on occasionally when I need cooling down more than having the window open can allow. Don't really like it tbh, dries my eyes out a bit (and my wifes massively) - but on a scorching day on a long motorway schlep, hell yes!

I'm going to give it a go with climate control on all the time and see if it affects my fuel economy much.


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## ollienoclue (Jan 30, 2017)

On all the time, have done this in a myriad of cars for as long as I've been driving. If there is an auto mode I use that as well. Simply alter the temperature to suit.

Have worked in tractors as well where it runs 24/7. The affect on fuel economy is of no consequence.

A/C systems need to be kept in use to stop the compressor clutch from seizing and also to circulate the coolant within the system, which is what helps keep the seals intact.

But by far the biggest reason is to keep the plenum chamber in your car dry and smell free. If you don't use the A/C (which must be run even in winter) then damp can accumulate in the ventilation system and start to cause horrible smells or grow fungi. And you won't want to have to have that thing to pieces as it will be a PITA to meddle with.

Open all the vents, and if it's automatic let it do it's thing. Also let any rear vents stay open and vent as well.

Change the pollen filter as recommended by the handbook. Some of them even use activated carbon to control incoming odours and fumes from the outside.

Even on a cold or rainy day the air con will dehumidify the air and eventually dry the interior of the car out. In conjunction with the heater it can work quite happily to dry your clothes or footwells which is of particular relevance to me because:
imageupload


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## SuperchargedLlama (Apr 25, 2008)

I would NOT want to have to clean the inside of that out!

Following the advice from this thread I've been running mine on full auto now and will continue to do so for a while and see if there's any major affect on the fuel consumption. It definitely was a nice drive to and from work yesterday!


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## enc (Jan 25, 2006)

Rarely on unless it's super hot (rare in Manchester) or windows steamed up... frequently in Manchester:lol:
I actually like driving with the windows open when it's hot


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## Mikesphotaes (Jul 24, 2016)

I got mine regassed in March.

Up till then I only used the aircon every month or so.

So left it on all the time since March and got it regassed for free in May, when it started blowing warm air.

I have my doubts about seals etc getting dry if it's not used all the time!


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## Clarkey-88 (Apr 29, 2014)

I always run my climate control in 'auto' mode. It automatically turns the air conditioning on (unless you manually turn it off) It adjusts the temperature, blower speed & direction of air flow accordingly to reach the desired temperature. Once the desired temperature is achieved, the blowers slow and the airflow is directed to the windscreen and foot well. 

I seem to recall my owners manual stating that the air conditioning must be run for a minimum of 20 mins per month to keep the system in working order.


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## Bazsm (May 6, 2011)

CoOkIeMoNsTeR said:


> Full auto climate set to 17 degrees most of the time, only occasionally change the settings


Your car must be like an ice box!

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## firehorse (Sep 23, 2016)

Hi,


Mother-Goose said:


> Blimey...I just turn mine on occasionally when I need cooling down more than having the window open can allow. Don't really like it tbh, dries my eyes out a bit (and my wifes massively) - but on a scorching day on a long motorway schlep, hell yes!
> 
> I'm going to give it a go with climate control on all the time and see if it affects my fuel economy much.


I'm like you, turning it on only when necessary and on motorways.

I tried it with my usual journey of about 3 miles town driving (Auris Hybrid); normally 45-55mpg, with the climate control 35 mpg!


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## Darlofan (Nov 24, 2010)

firehorse said:


> Hi,
> 
> I'm like you, turning it on only when necessary and on motorways.
> 
> I tried it with my usual journey of about 3 miles town driving (Auris Hybrid); normally 45-55mpg, with the climate control 35 mpg!


I wouldn't say a 3 mile journey is an accurate measure of mpg. I only lose about 10mpg when towing the caravan for hundreds of miles.


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## firehorse (Sep 23, 2016)

Hi,


Darlofan said:


> I wouldn't say a 3 mile journey is an accurate measure of mpg. I only lose about 10mpg when towing the caravan for hundreds of miles.


I'm just going by what the car is telling me. If the engine goes on, the mpg goes down. If the run for a while in electric mode the mpg goes up. I consistently get 45-55mpg on my journey depending on traffic and temperature (more warming required in the winter).

When I tried it once recently with aircon instead of opening the windows, the mpg as reported by the car was 35mpg.

If I consistently did that journey and used the aircon on that journey then my long term mpg would be about 35mpg rather than my usual 55mpg.

Normally, the longer I drive in the hybrid, the higher mpg is. It seems to use the battery to balance when I need power (petrol) and when I pootle along (electric).

On the motorway, when I used the aircon, I hardly noticed the difference in mpg with aircon on and off (no caravan  )


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## Darlofan (Nov 24, 2010)

firehorse said:


> Hi,I'm just going by what the car is telling me. If the engine goes on, the mpg goes down. If the run for a while in electric mode the mpg goes up. I consistently get 45-55mpg on my journey depending on traffic and temperature (more warming required in the winter).
> 
> When I tried it once recently with aircon instead of opening the windows, the mpg as reported by the car was 35mpg.
> 
> ...


Maybe hybrids are affected more, I know nothing about where the air con etc take energy from. I do 30k ish Miles a year and there is virtually no difference in mpg in summer winter with roof box etc on over 000s of miles.


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## Bazsm (May 6, 2011)

I just use the aircon in the car all the time because I like it to be cool in the cabin. Fuel consumption has no bearing on whether or not I use it.


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## GleemSpray (Jan 26, 2014)

All of this is subject to the size of the car engine, that is also being asked to spin an air conditioning compressor. 

Smaller engines will see noticeably reduced acceleration and mpg, whereas a bigger car engine will absorb the extra work more easily. 

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## Clarkey-88 (Apr 29, 2014)

GleemSpray said:


> All of this is subject to the size of the car engine, that is also being asked to spin an air conditioning compressor.
> 
> Smaller engines will see noticeably reduced acceleration and mpg, whereas a bigger car engine will absorb the extra work more easily.
> 
> Sent from my HTC 10 using Tapatalk


This is spot on. On my daily car ( a Mondeo 3.0 V6) I can't notice any difference at all when the air con is on. However, my other halves car (a fiesta 1.6) you can notice a dramatic drop in power every time the compressor clicks


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## jr2007 (Oct 5, 2016)

The aircon in my CL is designed to be on all the time. I haven't noticed any difference with or without but as has already been suggested earlier, engine size will likely make all the difference. I get around 20mpg regardless of whether the system is on or off, but then I have a 5.5L V8 powering everything.


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## SuperchargedLlama (Apr 25, 2008)

After seeing this thread I've been running the Climate Control on the entire time, just to see if there's a big difference or not.

I'm also driving a 1.6 Fiesta Titanium (Petrol) and have seen a drop of around 4-6mpg per tank according to the computer (3 tanks in now). Obviously right now it's particularly bad as it's so hot- I'm getting the unit re-gassed tomorrow as I read that they only ever half fill them in the factory and it's 8 years old, so could do with a refresh. It'll be interesting to see if the fuel efficiency is any better if the A/C is more efficient at cooling.


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## GleemSpray (Jan 26, 2014)

I could not figure out why some American citiy centres often have notices up that it is a violation and fine if you are caught parked with your engine running, then i realised it is the very necessary evil of air-con leading to pollution !!


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## SuperchargedLlama (Apr 25, 2008)

GleemSpray said:


> I could not figure out why some American citiy centres often have notices up that it is a violation and fine if you are caught parked with your engine running, then i realised it is the very necessary evil of air-con leading to pollution !!


I hadn't thought of that! It all becomes clear...


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## Alsone (May 19, 2010)

Best way to use aircon is to have it on permanently or almost permanently.

The reason is simple, unused the condensor seals dry out, crack and split and the aircon unit fails = expensive repair.

Simply using it, keeps the seals lubricated and prevents this. Also not many people realise it but in winter it dehumidifies the air and so prevents / removes misting much quicker than the fan system alone.

As a complete aside, does anyone know of a really good antibacterial air con treatment that treats the condensor as well as the vents?


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## LeeH (Jan 29, 2006)

I disagree ^^

Use it periodically to keep it maintained but nearly all the time, no not me. 

It makes a noticeable difference on fuel so unless you like burning cash away use it when it's hot and for de misting. 


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## Bazsm (May 6, 2011)

LeeH said:


> It makes a noticeable difference on fuel so unless you like burning cash away use it when it's hot and for de misting.


Depends what car/engine you have, it makes no difference in mine!

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